Actron Automobile Accessories CP9087 User Manual
®
IGNITION MODULE  
&
ENGINE SENSOR TESTER  
POWER OFF  
CP9087  
TM  
PROFESSIONAL  
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Index  
Vehicle Service Information ...................... Inside front cover  
Safety Precautions ............................................................... ii  
Section  
Tester Basics ............................................. 1-1  
1
2
Testing Sensors ..........................................2-1  
• Troubleshooting Tips .......................................... 2-1  
• Engine Coolant Temperature.............................. 2-2  
• Inlet Air Temperature .......................................... 2-3  
• Throttle Position (TP) .......................................... 2-6  
• EGR Valve Position (EVP) ................................ 2-14  
• Oxygen .............................................................. 2-18  
• Engine Knock .................................................... 2-26  
• Manifold Absolute Pressure (MAP/BARO) ....... 2-28  
• Mass Air Flow (MAF) ........................................ 2-34  
• Vane Air Flow .................................................... 2-40  
• Crankshaft/Camshaft Position .......................... 2-46  
Magnetic Reluctance Type ......................... 2-49  
Hall Effect or Optical Type .......................... 2-51  
Testing Ignition Modules............................3-1  
3
4
More Uses for the Sensor Probe ...............4-1  
• "Circuit Tester" Voltage Check ........................... 4-1  
• Continuity Checks ............................................... 4-2  
• Diode Check........................................................ 4-4  
i
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Safety  
First  
General Safety Guidelines to Follow When  
Working on Vehicles  
• Always wear approved eye protection  
• Always operate the vehicle in a well-ventilated area. Do not inhale exhaust  
gases – they are very poisonous!  
• Always keep yourself, tools, and test equipment away from all moving or hot  
engine parts.  
• Always make sure the vehicle is in Park (automatic transmission) or Neutral  
(manual transmission) and that the parking brake is firmly set. Block the drive  
wheels.  
• Never lay tools on vehicle battery. You may short the terminals together,  
causing harm to yourself, the tools, or the battery.  
• Never smoke or have open flames near vehicle. Vapors from fuel or charging  
batteries are highly flammable and explosive.  
• Never leave vehicle unattended while running tests.  
• Always keep a fire extinguisher suitable for all types of fires handy.  
• Always turn ignition key OFF when connecting or disconnecting electrical  
components, unless otherwise instructed.  
• Use shop rags to cover fuel line fittings when connecting or disconnecting fuel  
lines. Avoid contact with fuel. Dispose of all rags properly.  
• Clean up all fuel spills immediately.  
• Keep away from engine cooling fan. On some vehicles, the fan may start up  
unexpectedly.  
• You must follow vehicle service manual cautions when working around the air  
bag system. If the cautions are not followed, the air bag may open unexpect-  
edly, resulting in personal injury. Note that the air bag can still open up several  
minutes after the ignition key is turned OFF (or even if the battery is discon-  
nected) because of a special energy reserve module.  
• Always follow vehicle manufacturer’s warnings, cautions, and service procedures.  
6-3  
ii  
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Section  
Tester  
1
Basics  
— Description of Controls and Accessories  
— Installing and Checking the 9 Volt Battery  
Note: Detailed procedures for testing sensors and ignition modules are  
located in Section 2 (sensors) and Section 3 (ignition modules).  
Controls power to the Tester and selects measure-  
ment range sensitivity (as required by various  
1
RANGE sensor tests).  
Switch  
• POWER OFF - No power supplied to either the  
tester or RED test lead.  
• LOW - Tester powered up for use. Voltage from  
9 volt battery supplied to RED test lead. Selects  
range for measuring low levels of voltage,  
resistance or frequency.  
• HIGH - Tester powered up for use. Voltage from  
9 volt battery supplied to RED test lead. Selects  
range for measuring higher levels of voltage,  
resistance or frequency.  
Selects the type of signal being measured (for  
conducting sensor and ignition module tests). Different  
2
kinds of signals are used by various sensors.  
FUNCTION  
• VOLTS - Measures voltages. This function is used  
to test most sensors.  
Switch  
• OHMS - Measures resistance. Also used for  
checking continuity and testing diodes (see section  
4). Mostly used for testing temperature sensors.  
• FREQUENCY - Measures frequency signals.  
(Peak signal voltage must be at least 3 volts  
to register.) Some MAP and MAF sensors  
send a frequency signal. This function is  
also used to test ignition modules.  
1-1  
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Section 1  
A single TEST light turns on to show the level of a measured signal  
3
(voltage, resistance or frequency). When signal values are low, the  
TEST light is off or near the bottom of the column. The TEST light  
moves higher up the column as the signal level increases.  
TEST  
Lights  
Sensor tests involve working the sensor and watching the TEST  
light move up, down or flash. Note that the motion of the light is  
more important than its actual position.  
Used when testing ignition modules. The PULSE light will flash  
if the module is good.  
4
PULSE  
Note that the PULSE light will also be on (or flash) whenever  
Light frequency signals are being measured - this is normal.  
These lights are active when the tester switches are set to LOW  
VOLTS only.  
5
RICH/  
• LEAN (green): ON for voltages between 0.1 and 0.59 volts.  
LEAN  
• RICH (red): ON for voltages above 0.6 volts.  
Lights The RICH/LEAN lights work along with the TEST lights and are  
helpful when testing oxygen sensors. The RICH/LEAN lights may be  
ignored when testing other sensors using the LOW VOLTS range.  
Two or more of these are used for the various tests and checks.  
6
Yellow - The SIGNAL lead. Signals probed by this lead cause  
the TEST lights to react. Usually connected to a sensor or  
ignition module output circuit during testing.  
Test  
Leads  
Black - The COMMON lead. Used as a circuit ground or signal  
reference point for all tests and checks. This lead is always  
used.  
Green - The TRIGGER lead. Used when testing ignition  
modules. Sends a signal to “fire” the module. Usually connected  
to the module crankshaft/camshaft input circuit.  
Red - The 9V power lead. This lead is connected to the 9 volt  
battery inside the tester whenever the RANGE switch is in the  
LOW or HIGH positions. Ignition modules and some sensors  
require this power for testing.  
1-2  
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Tester Basics  
6
IGNITION MODULE &  
TEST  
ENGINE SENSOR TESTER  
3
HIGH  
LOW  
1
POWER OFF  
RICH  
RANGE  
Select  
5
LOW,  
VOLTS  
LEAN  
VOLTS  
OHMS  
2
4
FREQUENCY  
FUNCTION  
PULSE  
7
SIGNAL  
COMMON  
TRIGGER  
POWER 9V  
9V BATTERY TEST: 1) SET RANGE TO HIGH.  
2) SET FUNCTION TO OHMS. 3) DISCONNECT ALL LEADS.  
O.K. IF TOPMOST TEST LIGHT IS ON. WEAK IF ANOTHER LIGHT IS ON.  
8
9
Allows test lead to probe sensor circuits when the sensor is  
connected to vehicle wiring harness.  
7
Backprobe  
Adapter  
• Slide the “scooped” end of adapter next to circuit wire  
entering rear of connector.  
• Continue pushing adapter until it touches terminal inside  
connector. (Slightly twisting adapter while pushing may  
ease entry)  
To Sensor  
• Grasp open end of adapter with test lead clip. Keep  
pushing on adapter to maintain circuit contact.  
Caution: The “scooped” end of the  
adapter will break if you bend it.  
To Computer  
1-3  
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Section 1  
Tester Basics  
Used when checking some ignition modules. Makes  
extra connections as required for testing.  
8
Jumper Lead  
Used for easier attachment of test leads to certain  
sensor or wiring connector pins.  
9
Connector  
Pin Adapters  
• Push one end of the adapter onto the desired  
connector pin.  
• Grasp the other end with the test lead clip.  
A 9-volt transistor radio battery must be installed to  
power the unit. Use an alkaline battery (conventional  
batteries are too weak for ignition module testing).  
Sensor  
Tester  
Power  
Installing the Battery  
1. Hold the tester face down with both hands.  
2. Using both thumbs, firmly press downwards and  
outwards on the battery compartment door at the  
bottom of the tester.  
3. Slide the battery compartment door away from the  
tester to remove.  
4. Attach battery to connector and install inside  
compartment.  
5. Replace battery door. Slide door inwards until it  
snaps closed.  
Checking the Battery  
1. Make sure none of the test leads are connected  
together or touching anything.  
HIGH  
TEST  
LOW  
POWER OFF  
RANGE  
2. Set RANGE switch to HIGH.  
VOLTS  
3. Set FUNCTION switch to OHMS.  
OHMS  
FREQUENCY  
4. Battery is good if the top TEST light is ON. If any light  
below the top TEST light is ON, the battery is too  
weak for reliable testing and should be replaced.  
FUNCTION  
TIP: To extend battery life, always switch to POWER  
OFF when not making a measurement. This is safe to  
do even if the tester is connected to a circuit.  
1-4  
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Secti2on  
Testing Sensors  
Save yourself time! Always begin with a thorough  
visual and “hands-on” inspection. You can often  
find the cause of many problems by just looking.  
Troubleshooting  
Tips  
• Has the vehicle been serviced recently?  
Sometimes things get reconnected in the wrong  
place, or not at all.  
• Don’t take shortcuts. Inspect hoses and wiring  
which may be difficult to see due to location.  
• Inspect the air cleaner and ductwork for defects.  
• Check sensors and actuators for damage.  
• Inspect all vacuum hoses for:  
HVAC  
CRUISE  
YST  
CE BOOSTER  
EGR  
VAC  
BRAKE BOOSTER  
G GAP  
REG  
– Correct routing. Refer to vehicle service  
manual, or Vehicle Emission Control Information  
(VECI) decal located in the engine compartment.  
FUEL  
PRESS  
REG.  
TO TRANS  
MODE  
U.S.A.  
EGR  
VAC  
REG  
FRONT  
OF CAR  
EM  
– Pinches and kinks.  
12RAC8  
– Splits, cuts or breaks.  
• Inspect wiring for:  
– Contact with sharp edges (this happens often).  
– Contact with hot surfaces, such as exhaust  
manifolds.  
– Pinched, burned or chafed insulation.  
– Proper routing and connections.  
• Check electrical connectors for:  
– Corrosion on pins.  
– Bent or damaged pins.  
– Contacts not properly seated in housing.  
– Bad wire crimps to terminals.  
2-1  
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Section 2  
Engine TEMPERATURE  
HIGH  
SENSOR  
RESISTANCE  
LOW  
Cold  
Hot  
Typical Engine Coolant  
Temperature Sensor  
TEMPERATURE  
The engine temperature sensor is a thermistor - a  
resister whose resistance changes with tempera-  
ture. The hotter the sensor gets, the lower the  
resistance becomes. The thermistor is mounted  
inside the tip of a threaded metal housing. This is a  
2-wire sensor. (Exception: some Chrysler engines  
have a dual sensor with three wires.)  
What is It?  
The computer needs to know engine temperature  
so it can modify air/fuel ratios, spark advance, idle  
speed, and emission device operation (such as an  
EGR valve).  
How is It  
Used?  
Location  
The sensor is usually threaded into the engine  
block, lower intake manifold, or cylinder head to  
provide direct contact with coolant.  
• Related trouble codes sent by computer.  
When to Test  
• Driveability problems such as hard starting,  
rough idle, stalling, hesitation, stumble, surging,  
knocking (pinging), poor fuel economy, or black  
exhaust smoke.  
What to  
Inspect  
Sensor operation (see test on page 2-4). Poor  
connections at sensor or computer. Faulty sensor  
wiring (open or short circuits). Heavy deposits on  
sensor tip which can cause poor response.  
Leakage into sensor housing. Engine running too  
hot (problems with antifreeze, thermostat, water  
pump, fan, belts, low engine oil).  
2-2  
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Air TEMPERATURE  
HIGH  
SENSOR  
RESISTANCE  
LOW  
Cold  
Hot  
Typical Air Temperature Sensor  
TEMPERATURE  
What is It? The air temperature sensor is a thermistor - a  
resister whose resistance changes with temperature.  
The hotter the sensor gets, the lower the resistance  
becomes. The thermistor is mounted inside the tip of  
a threaded metal housing. This is a 2-wire sensor.  
The computer needs to know air temperature to  
calculate the amount of air entering the engine.  
Then, the computer can provide the proper air/fuel  
mixture for the desired operating condition.  
How is It  
Used?  
Location The sensor is threaded into the intake manifold,  
throttle body, rear of air cleaner assembly or  
elsewhere along the path of air entering the  
engine. Sometimes this sensor is built into a vane  
airflow meter or mass airflow sensor assembly.  
One connector handles both the air flow and  
temperature sensor circuits.  
When to Test  
• Related trouble codes sent by computer.  
• Driveability problems such as hard starting,  
rough idle, stalling, hesitation, stumble, surging,  
poor fuel economy, or black exhaust smoke.  
Sensor operation (see test on page 2-4). Poor  
connections at sensor or computer. Faulty sensor  
wiring (open or short circuits). Heavy deposits on  
sensor tip which can cause poor response.  
Restricted or blocked air passageways.  
Engine running too hot (problems with  
antifreeze, thermostat, water pump, fan, belts,  
low engine oil).  
What to  
Inspect  
2-3  
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Section 2  
Testing Sensors  
Temperature Sensor Test Procedure  
Use this procedure for testing all engine coolant or inlet air temperature sensors.  
Exceptions:  
• Certain Toyota, Nissan and Ford engines using vane airflow sensors have the  
air temperature sensor built into the vane airflow assembly. Refer to page 2-40  
for testing.  
• GM 1988 2.8L Mass Airflow Sensor (5 pin only) also has a built-in air tempera-  
ture sensor. Use same test procedure as for vane airflow temperature sensor.  
Refer to page 2-34 for testing.  
Sensor may be tested on or off vehicle.  
Warning: On-car testing involves running engine. Observe all safety precautions  
(see page ii). Work in well ventilated area.  
1) Verify ignition key is OFF.  
Allow engine to cool to outside temperature before testing.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF  
when done.  
3) Disconnect wiring harness from sensor - Inspect for  
damage.  
Some vehicles use a metal snap ring to secure wiring  
harness to sensor. Remove this snap ring before discon-  
necting wiring harness.  
4) Off-Car testing only: Remove sensor.  
Be careful of coolant spillage from mounting hole if  
removing engine temperature sensor.  
5) Connect test leads.  
• YELLOW to either sensor pin.  
• BLACK to remaining sensor pin.  
Black  
Yellow  
2-4  
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Engine Air TEMPERATURE  
6) Verify test clips make good contact and do not touch each  
other.  
HIGH  
Make sure red and green test clips are not touching anything.  
7) Set RANGE switch to HIGH.  
LOW  
POWER OFF  
RANGE  
8) Set FUNCTION switch to OHMS.  
VOLTS  
OHMS  
FREQUENCY  
9) Note TEST light position on tester.  
FUNCTION  
If the sensor is good, the light will move downwards as the  
sensor heats up.  
10) On-Car test only: Disconnect test leads and reconnect  
sensor to vehicle wiring harness.  
11) Heat sensor tip thoroughly.  
On-Car test: Start engine and idle at 2000 RPM until upper  
radiator hose is hot.  
Off-Car test:  
– Dip sensor tip into boiling water, OR...  
– (metal sensor housing) Heat tip with flame from candle or  
cigarette lighter OR...  
– (plastic sensor housing) Heat tip with hair dryer.  
12) On-Car test only: Turn ignition key OFF. Disconnect  
vehicle wiring harness from sensor and reconnect test  
leads as before.  
13) Observe TEST light position for test results.  
• Good Sensor - TEST light moved downwards below original  
position. (TEST light may go off if sensor is very hot - this is  
OK.) The TEST light will move upwards as the sensor cools  
off. Range of TEST light movement varies with sensor type  
and temperature change.  
• Bad Sensor - TEST light position did not change during test.  
14) Testing is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads.  
2-5  
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Section 2  
Testing Sensors  
TYPICAL THROTTLE POSITION SENSORS  
HIGH  
What Throttle Position Sensor  
SIGNAL  
VOLTAGE  
The throttle position sensor is a  
is It?  
potentiometer - a type of variable  
resistor (similar to a dashboard  
dimmer control). These sensors come  
in a wide variety of styles - some with  
connectors at the end of a short wire  
“pigtail”. The computer supplies power  
LOW  
MIN.  
MAX.  
ROTATION  
and ground to the sensor. The sensor has an element which is  
turned (rotary type) or pushed (linear type). When the sensor is  
mounted on the engine, the element is linked to the throttle so  
they move together. The sensor sends a voltage signal back to  
the computer indicating element (and thus throttle) position. The  
voltage signal increases when the throttle opens and operates  
the sensor element. Throttle position sensors on Asian vehicles  
may also include one or two throttle position switches.  
Throttle Position Switch  
This is one or two switches usually built into a single housing  
(often resembling a throttle position sensor). Movement of the  
throttle linkage operates the throttle switches. The switches are  
wired to the computer. The computer usually supplies an  
ground connection to one side of each switch.  
• The idle position switch is closed (or open - depends upon  
vehicle) when the throttle is resting. The switch operates  
when the throttle is opened (by any amount) and no longer in  
the idle position.  
2-6  
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THROTTLE POSITION Sensor/Switch  
• Sometimes a second switch is used to signal a wide  
open throttle condition. This switch is normally open (or  
closed - depends upon vehicle) when the throttle is at  
idle or just partially open. The switch operates when the  
throttle is opened beyond a certain point. (The amount of  
throttle opening required to operate the switch varies  
with vehicle.)  
The computer uses throttle position to determine engine  
operating condition: idle (closed throttle), cruise (part  
throttle), or hard acceleration (wide open throttle). The  
computer can then properly control air/fuel mixtures, spark  
advance, idle speed, and lock-up torque converters.  
How it is  
used?  
Location  
Fuel injected engines: Rotary type sensor - usually  
mounted to outside of throttle body and linked to throttle  
shaft.  
Computer controlled carburetor engines: Linear (sliding)  
type - usually mounted inside carburetor (GM) or outside  
carburetor (Ford).  
• Related trouble codes sent by computer.  
When to  
Test  
• Driveability problems such as hard starting, rough idle,  
stalling, hesitation, stumble, surging, knocking (pinging),  
poor fuel economy, backfiring, no torque converter lock-up.  
Sensor operation (see test on page 2-10) or switch  
operation (see test on page 2-12). Poor connections at  
sensor or computer. Sensor position adjustment. Faulty  
sensor wiring (open or short circuits). Binding throttle shaft  
or linkage. If used: “Cruise Control” linkage problems, idle  
speed control motor, vacuum hose connected to throttle  
positioner, choke, or cam systems affecting throttle  
position.  
What to  
Inspect  
2-7  
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Section 2  
Testing Sensors  
Throttle Position Sensor Connectors  
= Test A, page 2-10  
Some sensors require more than one test.  
= Test B, page 2-12  
A
B
Note: If the Red and Black test lead hook-ups are reversed,  
the TEST light will move in the opposite direction during Test A.  
This does not affect the accuracy of the test or harm the sensor.  
GM  
FORD  
FORD  
HONDA  
Black  
Red  
Yellow  
Black  
Yellow  
A
A
Red  
GM, FORD, CHRYSLER, HONDA  
Black  
Yellow  
Red  
Yellow  
A
A
Black  
Red  
HONDA  
HONDA  
Yellow  
A
A
A
Black  
Red  
Black  
Red  
Black  
Red  
Yellow  
Yellow  
Refer to vehicle service manual for connectors  
not shown. Hook up as follows:  
• Red test lead to sensor power pin  
• Yellow test lead to sensor signal pin  
• Black test lead to sensor ground pin  
2-8  
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THROTTLE POSITION Sensor/Switch  
TOYOTA  
TOYOTA/NISSAN  
A
B
Red Yellow Black  
Yellow Black  
Not used on some  
vehicles. Perform this  
test only if vehicle  
mating connector has  
3 wires.  
B
B
Yellow Black  
Black Yellow  
A
Red  
Yellow  
Black  
Yellow  
Black  
Black  
Not used on some  
vehicles. Perform  
this test only if  
vehicle mating  
connector  
Yellow  
B
B
Some sensors have  
cable attached here.  
Testing is identical.  
has 3 wires.  
2-9  
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Section 2  
Testing Sensors  
TEST A - Throttle Position Sensor  
Important: If more than one hook-up is shown, it means more than one test is  
required to check all parts of the sensor. Do all tests shown for your sensor.  
The letter next to the hook-up refers to the test procedure.  
Sensor may be tested on or off vehicle. (Exception: On-car test only for most  
Honda - sensor permanently attached to throttle body.)  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF when  
done.  
3) Disconnect wiring harness from sensor - Inspect for  
damage.  
Some vehicles use a metal snap ring to secure wiring harness  
to sensor. Remove this snap ring before disconnecting wiring  
harness.  
4) Off-Car testing only: Remove sensor.  
IMPORTANT: Many throttle position sensors require special  
adjustment when reinstalled. Refer to vehicle service manual  
for adjustment procedure. A good sensor will not perform  
properly if incorrectly adjusted.  
5) Connect test leads.  
Connect TEST leads according to diagram A in the compo-  
nent drawing.  
6) Verify test clips make good contact and do not touch  
each other.  
Make sure unused clips are not touching anything.  
2-10  
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THROTTLE POSITION Sensor/Switch  
7) Honda only: 1988-92 Civic and CRX  
– Remove vacuum hose from dashpot diaphragm.  
– Apply 20 in. Hg to the dashpot diaphragm using a hand  
vacuum pump.  
– The dashpot diaphragm is part of the throttle body  
assembly. It is used to control cold engine fast idle and  
HIGH  
throttle closure speed so engine will not stall.  
LOW  
POWER OFF  
8) Set RANGE switch to HIGH.  
RANGE  
VOLTS  
9) Set FUNCTION switch to VOLTS.  
OHMS  
FREQUENCY  
10) Operate sensor - Watch TEST light for results.  
FUNCTION  
(Note: TEST light may be on or off before sensor is  
operated.)  
On-Car test: Slowly move throttle linkage back and forth from  
idle to wide open position.  
Off-Car test: Slowly rotate sensor element back and forth  
from end to end.  
• Good Sensor - TEST light smoothly moves up or down as  
sensor is operated. (The TEST light may go off if it moves  
to the bottom of the column - this is O.K.) Range of TEST  
light movement varies with sensor type and vehicle  
mounting.  
• Bad Sensor - TEST light position does not change during  
test OR light movement is erratic, showing a sudden jump  
or dip during smooth sensor operation.  
11) Testing is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads.  
2-11  
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Section 2  
Testing Sensors  
TEST B - Throttle Position Switch  
Important: If more than one hook-up is shown, it means more than one test is  
required to check all parts of the switch. Do all tests shown for your switch. The  
letter next to the hook-up refers to the test procedure.  
Switch may be tested on or off vehicle.  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF when  
done.  
3) Disconnect wiring harness from switch - Inspect for  
damage.  
Some vehicles use a metal snap ring to secure wiring  
harness to switch. Remove this snap ring before disconnect-  
ing wiring harness.  
4) Off-Car testing only: Remove switch.  
IMPORTANT: Many throttle position switches require special  
adjustment when reinstalled. Refer to vehicle service manual  
for adjustment procedure. A good switch will not perform  
properly if incorrectly adjusted.  
5) Connect test leads.  
Connect TEST leads according to diagram B in the compo-  
nent drawing.  
6) Verify test clips make good contact and do not touch  
each other.  
Make sure unused clips are not touching anything.  
2-12  
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THROTTLE POSITION Sensor/Switch  
HIGH  
LOW  
POWER OFF  
7) Set RANGE switch to HIGH.  
RANGE  
8) Set FUNCTION switch to OHMS.  
VOLTS  
OHMS  
9) Operate sensor - Watch TEST light for results.  
FREQUENCY  
FUNCTION  
On-Car test: Slowly move throttle linkage back and forth  
from idle to wide open position.  
Off-Car test: Slowly rotate sensor element back and forth  
from end to end.  
• Good Switch - TEST light switches between  
TEST  
TEST  
being ON at top of column and OFF  
• Bad Switch - TEST light always ON at top of  
column or always OFF.  
10) Testing is complete.  
Set RANGE switch to POWER OFF and  
remove all test leads.  
2-13  
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Section 2  
Testing Sensors  
FORD  
EGR Valve  
HONDA  
EGR Valve  
What is it? This sensor is a potentiometer - a type of variable  
resistor (similar to a dashboard light dimmer  
HIGH  
control). The computer supplies power and ground  
to the sensor. the sensor has a shaft which is  
SENSOR  
pushed. When the sensor is mounted on the EGR  
valve, the shaft gets pushed as the valve opens.  
The sensor sends out a voltage signal indicating  
the amount of valve opening (“lift”). The voltage  
signal gets larger the more the valve is opened.  
VOLTAGE  
LOW  
MIN.  
VALVE OPENING  
MAX.  
The computer is programmed to provide optimum  
EGR flow during idle, cruise, and hard acceleration  
operating conditions. The computer uses the  
sensor signal to calculate actual EGR flow. Then  
the computer can modify the EGR valve opening  
as required.  
How it is  
used?  
Location Attached to the top of the EGR valve.  
• Related trouble codes sent by computer.  
When to Test  
• Driveability problems such as hesitation,  
stumble, surging, poor fuel economy, erratic  
acceleration, knocking (pinging), no torque  
converter lock-up.  
Sensor operation (see page 2-15). Poor connec-  
tions at the sensor or computer. Damaged or  
sticking EGR valve. Worn or broken vacuum  
hoses, vacuum connectors. Damaged vacuum  
reservoir, canister. Problems with control solenoids  
supplying operating vacuum to open EGR valve.  
What to  
Inspect  
2-14  
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EGR Valve Position/Lift Sensors  
EGR Valve Position Sensor Test Procedure  
Sensor may be tested on or off vehicle.  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Disconnect wiring harness from sensor - Inspect  
for damage.  
Some vehicles use a metal snap ring to secure  
wiring harness to sensor. Remove this snap ring  
before disconnecting wiring harness.  
4) Off-Car testing only: Remove sensor.  
Note: Some sensors are permanently attached to  
the EGR valve and cannot be removed.  
5) Connect test leads according to diagram.  
6) Verify test clips make good contact and do not  
touch each other.  
Make sure unused clips are not touching anything.  
HIGH  
LOW  
POWER OFF  
7) Set RANGE switch to HIGH.  
RANGE  
8) Set FUNCTION switch to VOLTS.  
VOLTS  
OHMS  
9) Operate sensor - Watch TEST light for results.  
FREQUENCY  
FUNCTION  
(Note: TEST light may be on or off before sensor is  
operated.)  
On-Car test:  
– Remove vacuum control hose from EGR valve.  
– Connect hand vacuum pump to EGR valve.  
– Gradually apply vacuum to slowly open valve.  
2-15  
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Section 2  
Testing Sensors  
Off-Car test: Slowly push sensor element back and forth  
from end to end.  
• Good Sensor - TEST light smoothly moves up or down as  
sensor is operated. (The TEST light may go off if it moves  
to the bottom of the column - this is O.K.) Range of TEST  
light movement varies with sensor type and vehicle  
mounting.  
• Bad Sensor - TEST light position does not change during  
test OR light movement is erratic, showing a sudden jump  
or dip during smooth sensor operation.  
10) Testing is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads.  
2-16  
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EGR Valve Position/Lift Sensors  
Sensor Connectors  
Note: If the Red and Black test lead hook-ups are reversed,  
the TEST light will move in the opposite direction during the  
test. This does not affect the accuracy of the test or harm  
the sensor.  
Black  
FORD  
Yellow  
Red  
Honda uses two  
sensor types. Try  
hook-up #1 first.  
If good test  
HONDA – #1  
HONDA – #2  
results are not  
obtained, retest  
using hook-up #2  
before judging  
sensor.  
Red  
Yellow  
Red  
Black  
Yellow  
Black  
Refer to vehicle service manual for connectors  
not shown. Hook up as follows:  
• Red test lead to sensor power pin  
• Yellow test lead to sensor signal pin  
• Black test lead to sensor ground pin  
2-17  
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Section 2  
Testing Sensors  
Typical Oxygen Sensor  
What is It? The oxygen sensor is a zirconium dioxide ceramic  
mounted in the tip of a threaded metal housing.  
The tip is perforated to protect the sensing element  
but still allow exhaust gases to pass through.  
The sensor produces a voltage signal based on the  
amount of oxygen it contacts. A low voltage  
indicates a lean exhaust (too much oxygen). A  
higher voltage signals a rich exhaust (not enough  
oxygen).  
The sensor must be very hot to operate: 349(C  
(660(F). Many have 2-wire heating elements built-  
in to quicken the warm-up time.  
The computer uses this sensor to calculate  
optimum air/fuel mixture for low emissions and  
good fuel economy. If the sensor indicates a rich  
How it is  
used?  
exhaust (not enough oxygen because of too much  
fuel), the computer will compensate by reducing  
fuel delivery. If the computer receives a lean signal  
(too much oxygen because of too little fuel), it will  
increase fuel delivery. NOTE: Some vehicles use  
more than one oxygen sensor.  
The sensor is threaded into the exhaust manifold to  
give it direct contact with the exhaust gases.  
Location  
2-18  
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OXYGEN  
HIGH  
SENSOR  
VOLTAGE  
LOW  
Lean  
OPTIMUM  
Rich  
AIR FUEL MIXTURE  
When to Test • Related trouble codes sent by computer.  
• Driveability problems such as rough running,  
hesitation, stumble, poor fuel economy, poor  
performance, black exhaust smoke.  
Sensor operation (see page 2-21). Poor connec-  
tions at the sensor or computer.  
Inspection  
This sensor often fails because of contamination  
from fuel, oil additives, gasket sealer or an overly  
rich running engine. Factors which can make a rich  
running engine include: ignition system problems  
(coil, distributor cap, rotor, spark plugs, wires), fuel  
contaminated by engine oil, emission devices  
(carbon canister, EGR valve, PCV valve, air  
injection system), manifold leaks, air filter, fuel  
pressure and engine not at normal operating  
temperature.  
IMPORTANT:  
Some engines (usually off-road applications)  
use a titania-type oxygen sensor. This sensor  
resembles the common zirconium type, but has  
an open-ended tip. The titania sensor changes  
resistance when it operates. This tester is  
not designed to test the titania type  
sensor.  
2-19  
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Section 2  
Testing Sensors  
1-Wire: Single wire goes to sensor SIGNAL.  
Sensor housing is connected to sensor GROUND.  
Sensor Types  
2-Wire: One wire goes to sensor SIGNAL. Second  
wire goes to sensor GROUND. Refer to vehicle  
service manual for wire identification. (Sensor wire  
is often black.)  
3-Wire: Two wires (often the same color) go to the  
sensor heating element. Third wire (different color  
from the others) goes to sensor SIGNAL. Sensor  
housing is connected to sensor GROUND.  
4-Wire: Two wires (often the same color) go to the  
sensor heating element. Third wire goes to sensor  
SIGNAL. Fourth wire goes to sensor GROUND.  
Refer to vehicle service manual for wire identifica-  
tion. (Signal wire is often black.)  
2-20  
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OXYGEN  
Heating Element Test  
• Do this test if sensor has a heating element (3 or 4 wire connector).  
• If sensor has 1 or 2 wire connector, do not do this test. Go directly to On-Car  
Test (page 2-22).  
Warning: Observe all safety precautions (see page ii) if testing sensor on vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF when done.  
3) Disconnect wiring harness from sensor - Inspect for damage.  
Some vehicles use a metal snap ring to secure wiring harness to  
sensor. Remove this snap ring before disconnecting wiring  
harness.  
4) Connect test leads.  
• YELLOW to either sensor HEATER pin.  
• BLACK to remaining sensor HEATER pin.  
5) Verify test clips make good contact and do not touch each  
HIGH  
other.  
LOW  
POWER OFF  
Make sure unused clips are not touching anything.  
RANGE  
6) Set RANGE switch to HIGH.  
VOLTS  
OHMS  
FREQUENCY  
7) Set FUNCTION switch to OHMS.  
FUNCTION  
8) Observe TEST light for test results.  
TEST  
• Good Heater: TEST light OFF (low resistance).  
• Bad Heater: TEST light ON in any position (resistance too  
high, or open circuit).  
9) Heating Element test is complete.  
• Set RANGE switch to POWER OFF and remove all test leads.  
• Go to On-Car Test.  
2-21  
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Section 2  
Testing Sensors  
On-Car Test  
Important: Reliable testing of the oxygen sensor while on-vehicle is very  
difficult because test conditions cannot be well controlled. If the sensor  
responds during on-car testing, then it is probably good and no other  
testing is necessary. If the sensor does not seem to respond when tested  
on-car, remove it and perform the off-car test before deciding whether or  
not the sensor is bad.  
Warning: This test involves running the engine. Observe all safety precautions  
(see page ii). Work in well-ventilated area.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF  
when done.  
3) Connect test leads.  
• YELLOW to sensor SIGNAL circuit.  
• BLACK to good vehicle GROUND.  
– Keep sensor connected to vehicle wiring and use  
backprobe adapter to contact sensor SIGNAL circuit if  
possible.  
– If you cannot use backprobe, disconnect sensor  
connector and connect YELLOW test lead directly to  
sensor SIGNAL pin. Note: Most computer systems will  
store a trouble code in memory (and turn on the “Check  
Engine” light) if engine is run with sensor disconnected.  
Ignore or erase the code after testing. Refer to Vehicle  
Service Manual.  
4) Verify test clips make good contact.  
HIGH  
LOW  
Make sure unused clips are not touching anything.  
POWER OFF  
RANGE  
5) Set RANGE switch to LOW.  
VOLTS  
OHMS  
6) Set FUNCTION switch to VOLTS.  
7) Start engine - Idle until hot.  
FREQUENCY  
FUNCTION  
Run engine until upper radiator hose is hot and  
pressurized.  
2-22  
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OXYGEN  
8) Observe RICH/LEAN lights during fast idle.  
• The TEST light column also indicates sensor voltage,  
but it is easier to check operation by watching the RICH/  
LEAN lights.)  
• Maintain throttle partially open (2000 RPM idle).  
– IF the RICH/LEAN lights flash back and forth every 3  
seconds or less...  
THEN the sensor is good and no further testing is  
necessary. Go to step 10.  
– IF it takes longer than 3 seconds for the RICH/LEAN  
lights to switch back and forth...  
THEN the sensor may be degraded. Go to step 10,  
then do the Off-Car test on page 2-24  
– IF the RICH/LEAN lights do not flash back and forth...  
THEN go to step 9.  
9) Observe RICH / LEAN lights during throttle changes.  
• Quickly move throttle from idle to partially open (2000  
RPM) position then back to idle. (This attempts to create  
a momentary rich or lean engine operating condition.)  
Repeat this throttle action several times while observing  
the RICH/LEAN lights.  
RICH  
RICH  
– IF the RICH/LEAN lights switch within 3 seconds of the  
throttle action...  
THEN the sensor is good and no further testing is  
necessary. Go to step 10.  
LEAN  
LEAN  
– IF it takes longer than 3 seconds for the RICH/LEAN  
lights to switch...  
THEN the sensor may be degraded. Go to step 10. Do  
the Off-Car test on page 2-24  
– IF the RICH/LEAN lights do not flash back and forth...  
THEN go to step 10. Do the Off-Car test on page 2-24.  
10) On-Car test is complete - Turn ignition key OFF.  
• Set RANGE switch to POWER OFF and remove all test  
leads.  
• If the RICH / LEAN lights did not flash, or flashed  
too slowly, in steps 8 or 9, then do the Off-Car test  
on page 2-24.  
2-23  
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Section 2  
Testing Sensors  
Off-Car Test  
Warning: This test involves use of an open flame from a propane torch.  
Observe all safety precautions for torch operation. Do not use near flammable  
material or gases.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Disconnect wiring harness from sensor - Inspect  
for damage.  
Some vehicles use a metal snap ring to secure wiring  
harness to sensor. Remove this snap ring before  
disconnecting wiring harness.  
4) Remove sensor.  
5) Firmly grasp sensor with a pair of locking pliers.  
6) Connect test leads  
• YELLOW to sensor SIGNAL pin.  
• BLACK to sensor GROUND.  
7) Verify test clips make good contact and do not  
touch each other.  
HIGH  
LOW  
Make sure unused clips are not touching anything.  
POWER OFF  
RANGE  
8) Set RANGE switch to LOW.  
VOLTS  
9) Set FUNCTION switch to VOLTS.  
OHMS  
FREQUENCY  
10) Light torch - Heat sensor tip - Observe RICH/  
FUNCTION  
LEAN lights.  
• Thoroughly heat sensor tip until tip is as hot as  
possible, but not “glowing”. See Fig. 1.  
• The sensor tip must be very hot to operate! (349(C,  
660(F)  
• The LEAN or RICH light should be ON. If both lights  
are off, the sensor is defective.  
2-24  
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OXYGEN  
11) Observe RICH/LEAN lights while operating  
sensor.  
• After sensor tip is hot. move the flame until the  
sensor tip is completely surrounded by the flame.  
This keeps oxygen away from the tip. See Fig. 2.  
– Good Sensor: RICH light turns ON within 3  
seconds indicating a “rich” (low oxygen) condition.  
– Bad Sensor: RICH light takes longer than 3  
seconds to turn on, or does not turn on at all.  
• Move flame so oxygen can reach sensor tip.  
(Keep sensor tip hot with flame.) See Fig. 1.  
– Good Sensor: LEAN light turns ON within 3  
seconds indicating a “lean” (high oxygen) condition.  
– Bad Sensor: LEAN light takes longer than 3  
seconds to turn on, or does not turn on at all.  
12) Repeat step 11 a few times to verify results.  
13) Testing is complete.  
Extinguish flame, set RANGE switch to POWER  
OFF, let sensor cool and remove test leads.  
IMPORTANT: Special anti-seize compound must be  
applied to sensor housing threads before reinstallation.  
Refer to vehicle service manual for proper type.  
RICH  
RICH  
LEAN  
LEAN  
Fig. 1  
Fig. 2  
2-25  
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Section 2  
Testing Sensors  
Yellow  
Yellow  
Black  
Black  
What is It? The knock sensor is a piece of piezoelectric  
material mounted in a metal housing. The sensor  
acts like a microphone - it changes vibrations into a  
small AC voltage signal. The sensor usually has a  
one wire or two wire connector.  
How it is The computer (or other spark timing controller) is  
designed to recognize sensor signals caused by  
used?  
engine knock vibrations. Then, spark timing is  
retarded to eliminate the damaging knock condition  
Location Usually threaded into (or bolted on) the engine  
block, intake manifold or exhaust manifold. Often  
near the cylinder heads.  
When to Test • Related trouble codes sent by computer.  
• Knocking during cruise or hard acceleration (not  
enough spark retard), hesitation, poor perfor-  
mance and fuel economy (excess spark retard).  
What to Sensor operation (see test on page 2-27). Poor  
connections at sensor or computer. Faulty sensor  
Inspect  
wiring (open or short circuits). Spark timing. Bad  
fuel quality.  
2-26  
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Engine KNOCK  
Knock Sensor Test Procedure  
Sensor may be tested on or off vehicle.  
Warning: Observe all safety precautions (see page ii) if testing sensor on vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery (refer to page 1-4).  
3) Disconnect wiring harness from sensor - Inspect for  
damage.  
4) Connect test leads to sensor.  
One-wire connector:  
• YELLOW test lead to signal pin (top of sensor).  
• BLACK test lead to body of sensor (off-car) or nearby  
ground (on-car).  
Two-wire connector:  
HIGH  
• YELLOW test lead to either sensor pin.  
LOW  
POWER OFF  
• BLACK test lead to remaining sensor pin.  
RANGE  
5) Set RANGE switch to LOW.  
VOLTS  
OHMS  
FREQUENCY  
6) Set FUNCTION switch to VOLTS.  
FUNCTION  
7) Operate sensor - Watch TEST light for results.  
(Note: Ignore any RICH/LEAN light flashes.)  
On-car test: Lightly tap surface near sensor using a  
socket extension (or similar tool) and a light hammer.  
Do not tap directly on sensor!  
Off-car test: Grasp sensor firmly. Gently tap sensor tip  
TEST  
with a light hammer.  
– Good sensor: TEST lights flash upward from the  
bottom of the TEST light column during a tap. (Only a  
few lights may flash. This is O.K.) Range of TEST light  
movement varies with sensor type and tapping force.  
– Bad sensor: TEST lights do not flash during a tap.  
8) Testing is complete.  
2-27  
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Section 2  
Testing Sensors  
FORD  
GM/CHRYSLER  
TOYOTA/HONDA  
Manifold Absolute Pressure (MAP) Sensor  
Barometric Pressure (BARO) Sens  
What is It? This sensor is an electronic module which sends a  
signal to the computer indicating atmospheric  
pressure and/or engine vacuum. Depending upon  
sensor type, the signal may be a dc voltage or a  
frequency. More pressure (less vacuum) makes the  
sensor signal increase (higher voltage or fre-  
quency). The computer supplies power and ground  
to the sensor.  
The computer needs to know air pressure both  
outside and inside the manifold to properly adjust  
the air/fuel mixture and ignition timing for varying  
engine load and altitude conditions. On turbo-  
charged engines, the computer also uses the  
sensor to monitor boost pressure and operate the  
wastegate accordingly.  
How it is  
used?  
2-28  
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Manifold Absolute Pressure MAP/BARO  
The sensor is mounted either on the bulkhead, air  
Location  
cleaner, throttle body or elsewhere in the engine  
compartment. A vacuum hose connects the sensor  
to a strong source of manifold vacuum. (Some new  
MAP sensor types may be directly mounted to the  
manifold, eliminating the vacuum hose connection.)  
The BARO sensors are vented to the atmosphere -  
there is no vacuum hose attached.  
Some Honda engines locate the MAP sensor inside  
a control box containing several vacuum hoses and  
solenoids.  
• Related trouble codes sent by computer.  
When to Test  
• No start, hard starting, stalling, rough idle,  
hesitation, stumble, surging, poor fuel economy,  
black exhaust smoke, knocking, backfiring,  
catalytic converter overheating or no torque  
converter lock-up.  
Vehicle  
FORD  
GM/CHRYSLER  
Harness  
Connectors  
for MAP  
Power  
Power  
MAP Signal  
Ground  
MAP Signal  
Sensor  
(Mating side of  
connector shown.)  
Ground  
TOYOTA  
HONDA  
Ground  
Power  
Power  
Ground  
Power  
Signal  
Ground Signal  
Signal  
Refer to vehicle service manual for connectors not shown.  
2-29  
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Section 2  
Testing Sensors  
Manifold Absolute Pressure (MAP) Sensor  
Test Procedure  
Testing is done on-vehicle.  
Warning: This test involves running the engine. Observe all safety  
precautions (see page ii). Work in well-ventilated area.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Connect test leads.  
Keep sensor connected to vehicle wiring.  
Yellow  
• YELLOW to sensor SIGNAL circuit. Use  
backprobe adapter.  
• BLACK to good vehicle GROUND.  
4) Verify test clips make good contact.  
Backprobe  
Make sure unused clips are not touching any-  
thing.  
5) Set switches:  
• RANGE on HIGH.  
• FUNCTION on VOLTS.  
Exception:  
Ford vehicles with frequency type sensor (see  
diagram).  
– RANGE on LOW.  
– FUNCTION on FREQUENCY.  
6) Turn ignition key ON but DO NOT START  
ENGINE.  
7) Note TEST light position on tester.  
• If the sensor is good, the light will move  
downwards when vacuum is applied.  
2-30  
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Manifold Absolute Pressure MAP/BARO  
• Note: If the TEST light is OFF a problem  
exists. Go to step 9 and continue testing to find  
cause.  
8) Operate sensor - Watch TEST light for  
results.  
(Note: Ignore any PULSE light action.)  
Non-Turbo Engines only: Start engine and let  
idle.  
Turbo Engines only: Attach hand vacuum  
pump to sensor vacuum port. Apply 18 in.  
vacuum. (More than 25 in. vacuum may damage  
sensor.)  
Good Sensor  
– TEST light moves downward during engine idle  
or when vacuum applied. (The TEST light may  
go off if it moves to the bottom of the column -  
this is O.K.)  
– Range of TEST light movement varies with  
sensor type and applied vacuum.  
– Note: if test results are O.K. but a computer  
trouble code indicates a bad sensor signal, the  
wire between the sensor signal pin and the  
computer may be open.  
– Testing is complete.  
Problem exists (Bad sensor or wiring)  
– TEST light position does not change during test.  
– Go to step 9 and continue testing to find cause.  
Do all steps to avoid replacing a good sensor!  
9) Ignition key OFF.  
HVAC  
CRUISE  
10) Check MAP sensor vacuum hose for...  
YST  
CE BOOSTER  
EGR  
VAC  
REG  
• Correct hook-up.  
BRAKE BOOSTER  
G GAP  
U.S.A.  
FUEL  
PRESS  
REG.  
TO TRANS  
MODE  
• Pinches, kinks or collapsed sides.  
• Splits, cuts, breaks or clogs  
EGR  
VAC  
REG  
FRONT  
OF CAR  
EM  
Repair as necessary, then retest. If no  
trouble found, go to next step.  
12RAC8  
2-31  
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Section 2  
Testing Sensors  
11) Check MAP sensor power circuit.  
Keep sensor connected to vehicle wiring.  
• YELLOW test lead to sensor POWER circuit.  
Use backprobe adapter.  
HIGH  
LOW  
POWER OFF  
• BLACK test lead to good vehicle GROUND.  
• RANGE on HIGH.  
RANGE  
VOLTS  
OHMS  
• FUNCTION on VOLTS.  
• Ignition key ON.  
FREQUENCY  
FUNCTION  
TEST  
Good power circuit: Top (or next to top) TEST  
light ON.  
Go to next step.  
Bad power circuit: TEST light OFF or not in top  
(or next to top) position.  
Repair open or short in power circuit wiring, then  
retest.  
12) Check MAP sensor ground circuit.  
• Same set-up as previous step, but move  
YELLOW test lead to sensor GROUND circuit.  
(Use backprobe adapter.)  
Good ground circuit: TEST light OFF.  
Go to next step.  
Bad ground circuit: Any TEST light ON.  
Repair open in ground circuit wiring, then retest.  
13) Check for connector problems.  
• Ignition key OFF.  
• Disconnect wiring harness from MAP sensor.  
(Some vehicles use a metal snap ring to secure  
wiring harness to sensor. Remove this snap ring  
before disconnecting wiring harness.)  
• Check terminals for damage, corrosion, bad  
wire crimps or improper seating in connector.  
Repair as necessary, then retest. If no trouble  
found, go to next step.  
2-32  
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Manifold Absolute Pressure MAP/BARO  
14) Check MAP signal wire for short to ground.  
•Verify ignition key OFF and MAP sensor wiring  
harness disconnected.  
HIGH  
LOW  
POWER OFF  
• RANGE on LOW.  
RANGE  
• FUNCTION on OHMS.  
VOLTS  
OHMS  
• YELLOW test lead to MAP signal pin on  
vehicle harness connector.  
FREQUENCY  
FUNCTION  
• BLACK test lead to good vehicle GROUND.  
Good circuit (no short): TEST light ON in any  
position.  
Go to next step.  
Bad circuit (shorted): TEST light OFF.  
Repair short in signal circuit wiring, then retest.  
15) Testing is complete.  
Verify ignition key OFF. Set RANGE switch to  
POWER OFF and remove all test leads.  
If steps 10 through 14 are all good (but step 8  
showed a problem) then the sensor is bad and  
needs to be replaced.  
2-33  
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Section 2  
Testing Sensors  
FLOW  
Typical  
MAF  
Sensor  
Mass Air Flow (MAF) Sensors  
This sensor is an electronic module which sends a  
What is It?  
signal to the computer indicating the amount of air  
entering the engine. Depending upon sensor type,  
the signal may be a dc voltage or a frequency. The  
signal level increases (higher voltage or frequency)  
as the air flow increases.  
Within the sensor is a heated wire located in the  
path of incoming air. The module determines air  
flow by measuring the temperature drop of the  
heated wire as air passes around it.  
The computer needs to know incoming air flow to  
properly adjust air/fuel mixture and ignition timing  
for varying engine load and operating conditions.  
How it is  
used?  
Location  
The sensor is mounted in the engine incoming air  
ducts—typically just behind the air cleaner assem-  
bly or near the throttle body.  
When to Test • Related trouble codes sent by computer.  
• Driveability problems such as hard starting,  
rough idle, stalling, hesitation, stumble, surging,  
knocking (pinging), poor fuel economy, black  
exhaust smoke, backfiring, catalytic converter  
overheating or no torque converter lock-up.  
2-34  
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Mass Air Flow MAF  
Vehicle Harness Connectors for MAF Sensor  
(Mating side of connector shown.)  
GM  
MAT SIGNAL  
MAT RTN  
POWER  
POWER  
GROUND  
MAF SIGNAL  
MAF SIGNAL  
GROUND  
1988 and Older  
1988 2.8L only  
RANGE on LOW  
RANGE on LOW  
FUNCTION on FREQUENCY  
FUNCTION on FREQUENCY  
GROUND  
MAF RETURN  
MAF SIGNAL  
BURN-OFF SIGNAL  
POWER  
POWER  
GROUND  
MAF SIGNAL  
1989 and Newer  
RANGE on HIGH  
All 5-Pin except 1988 2.8L  
RANGE on HIGH  
FUNCTION on FREQUENCY  
FUNCTION on VOLTS  
MAF SIGNAL  
Ford  
RANGE on HIGH  
FUNCTION on VOLTS  
MAF RETURN  
GROUND  
NOTE:  
MAF RETURN is  
not connected to  
vehicle GROUND.  
POWER  
Refer to vehicle service manual for connectors not shown.  
2-35  
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Section 2  
Testing Sensors  
Vehicle Harness Connectors for MAF Sensor  
(Mating side of connector shown.)  
Nissan  
MAF  
Ground Signal  
MAF  
Signal  
MAF  
Signal  
Ground  
Power  
Power  
Ground  
Power  
Pulsar NX SE  
All except 1987-88  
1987-88 Pulsar NX SE only  
MAF  
Signal  
MAF  
MAF  
Ground  
Power  
Ground Power  
Return Signal  
1987 Pulsar NX  
1987 Sentra (E16i)  
1988 Pulsar NX XE  
1988 Sentra  
1985-86 Maxima  
1985-86 300ZX  
1985-86 300ZX Turbo  
MAF  
Signal  
MAF  
Signal  
Power Ground  
Ground  
Power  
1987-88 Maxima  
1987-88 200SX SE  
1987-89 300ZX  
1989-90 Sentra  
1990 Pulsar NX  
MAF  
Signal  
MAF  
Return  
MAF  
Signal  
Ground  
Power  
Power  
Ground  
1989 and Up Maxima  
1990 and Up 300ZX  
All Nissan:  
RANGE on HIGH  
FUNCTION on VOLTS  
MAF  
MAF  
Signal  
Power  
Ground  
= May not be used  
Return*  
*May not be used  
2-36  
Refer to vehicle service manual for connectors not shown.  
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Mass Air Flow MAF  
Mass Air Flow (MAF) Sensor Test Procedure  
Testing is done on-vehicle.  
Warning: This test involves running the engine. Observe all safety  
precautions (see page ii). Work in well-ventilated area.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Connect test leads - refer to hook-up diagram.  
Keep sensor connected to vehicle wiring.  
• YELLOW to sensor SIGNAL circuit. Use  
backprobe adapter.  
• BLACK to good vehicle GROUND.  
4) Verify test clips make good contact.  
Make sure unused clips are not touching any-  
thing.  
5) Set switches - refer to hook-up diagram.  
6) Turn ignition key ON but DO NOT START  
ENGINE.  
7) Note TEST light position on tester.  
• Typically, the TEST light will be off, at the  
bottom of the column or blinking.  
• Ignore any PULSE light action.  
• If the sensor is good, the light will move upwards  
during engine run.  
8) Start engine and let idle - Watch TEST light for  
results.  
Good Sensor:  
– TEST light moves upward after engine starts.  
TEST light moves up even further if engine RPM  
is momentarily increased. (Move throttle to  
check.) Range of TEST light movement  
varies with sensor type and engine speed.  
2-37  
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Section 2  
Testing Sensors  
– Note: If test results are O.K. but a computer  
trouble code indicates a bad sensor signal, the  
wire between the sensor signal pin and the  
computer may be open.  
– Testing is complete.  
Problem exists (Bad sensor or wiring):  
– TEST light position does not change during test.  
– Go to step 9 and continue testing to find cause.  
Do all steps to avoid replacing a good sensor!  
– Note: Sensor is defective if TEST light jumps  
erratically when sensor GENTLY tapped with  
lightweight tool.  
9) Ignition key OFF.  
10) Check for air intake problems.  
• Air leaks - around MAF sensor, ductwork or  
throttle body.  
• Obstructions in air duct.  
• Clogged air filter.  
Repair as necessary, then retest. If no trouble  
found, go to next step.  
11) Check MAF sensor power circuit.  
Keep sensor connected to vehicle wiring.  
HIGH  
• YELLOW test lead to sensor POWER circuit.  
Use backprobe adapter.  
LOW  
POWER OFF  
RANGE  
• BLACK test lead to good vehicle GROUND.  
• RANGE on HIGH.  
VOLTS  
OHMS  
FREQUENCY  
• FUNCTION on VOLTS.  
• Ignition key ON.  
FUNCTION  
TEST  
Good power circuit: Top (or next to top) TEST  
light ON.  
Go to next step.  
Bad power circuit: TEST light OFF or not in top  
(or next to top) position.  
Repair open or short in power circuit wiring, then  
retest.  
2-38  
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Mass Air Flow MAF  
12) Check MAF sensor ground circuit.  
• Same set-up as previous step, but move YELLOW  
test lead to sensor GROUND circuit. Do not probe  
MAF RETURN pin. Use backprobe adapter.  
Good ground circuit: TEST light OFF.  
Go to next step.  
Bad ground circuit: Any TEST light ON.  
Repair open in ground circuit wiring, then retest.  
13) Check for connector problems.  
• Ignition key OFF.  
• Disconnect wiring harness from MAF sensor. (Some  
vehicles use a metal snap ring to secure wiring  
harness to sensor. Remove this snap ring before  
disconnecting wiring harness.)  
• Check terminals for damage, corrosion, bad wire  
crimps or improper seating in connector.  
Repair as necessary, then retest. If no trouble found, go  
to next step.  
14) Check MAF signal wire for short to ground.  
• Verify ignition key OFF and MAF sensor wiring  
harness disconnected.  
HIGH  
LOW  
POWER OFF  
• RANGE on LOW.  
RANGE  
• FUNCTION on OHMS.  
VOLTS  
OHMS  
• YELLOW test lead to MAF signal pin on vehicle  
harness connector.  
FREQUENCY  
FUNCTION  
• BLACK test lead to good vehicle GROUND.  
Good circuit (no short): TEST light ON in any position.  
Go to next step.  
Bad circuit (shorted): TEST light OFF.  
Repair short in signal circuit wiring, then retest.  
15) Testing is complete.  
Verify ignition key OFF. Set RANGE switch to POWER  
OFF and remove all test leads.  
If steps 10 through 14 are all good (but step 8  
showed a problem) then the sensor is bad and  
2-39  
needs to be replaced.  
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Section 2  
Testing Sensors  
Typical VAF Sensor  
Referred to as Vane Air Flow  
(VAF) sensor or Air Flow Meter  
AIR FLOW  
Vane Air Flow Sensors  
This sensor sends a dc voltage signal to the computer  
indicating the amount of air entering the engine. The  
voltage signal increases as the air flow increases. The  
sensor assembly has a pivoting door (“vane”) which is  
opened by incoming air. The vane is connected to a  
potentiometer (a variable resistor - like a dashboard  
dimmer control) which generates the voltage signal. Some  
sensor assemblies also contain an air temperature sensor  
or a vane position switch (or both).  
What  
is It?  
The computer needs to know incoming air flow to properly  
adjust air/fuel mixture and ignition timing for varying  
engine load and operating conditions.  
How it is  
used?  
The sensor is mounted in the engine incoming air duct -  
between the air cleaner and the throttle body.  
Location  
When to • Related trouble codes sent by computer.  
• Driveability problems such as hard starting, rough idle,  
Test  
stalling, hesitation, stumble, surging, knocking (ping-  
ing), poor fuel economy, black exhaust smoke, backfir-  
ing, catalytic converter overheating or no torque  
converter lock-up.  
Sensor operation (see tests on pages 2-43 through 2-44).  
Poor connections at sensor or computer. Faulty sensor  
wiring (open or short circuits). Airflow obstructions in  
ductwork or clogged air filter. Binding pivot on vane  
“door”. Air leaks around sensor or throttle body.  
What to  
Inspect  
2-40  
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Vane Air Flow VAF  
Sensor Connectors  
Toyota  
*Toyota uses  
two sensor  
types. Try  
1
2
3
5
6
7
1
2
3
5
6
7
4
4
hook-up #1  
first. If good  
test results are  
not obtained,  
retest using  
hook-up #2  
before judging  
sensor.  
B
C
Black  
Yellow  
Red  
Yellow  
A *  
Black  
#1  
1
2
3
5
6
7
1
2
3
5
6
7
4
4
A *  
Black  
Black  
Yellow  
Red  
Yellow  
#2  
Nissan  
*Nissan uses two sensor types. Try hook-up  
#1 first. If good test results are not obtained,  
retest using hook-up #2 before judging sensor.  
A *  
#1  
Black  
Red  
Yellow  
A *  
A
#2  
Red  
Yellow  
Yellow  
Black  
Black  
Black  
Black  
Yellow  
Red  
= NOT  
USED  
B
B
Yellow  
Ford  
A
B
Yellow  
Black  
Black  
Yellow  
Red  
Hook up as follows: Red lead to sensor power pin.  
Yellow lead to sensor signal pin.  
Refer to vehicle service manual  
for connectors not shown.  
2-41  
Black lead to sensor ground pin.  
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Section 2  
Testing Sensors  
TEST PREPARATION:  
All Air Flow Meter Sensor Tests  
IMPORTANT:  
• Test all hook-ups shown for the sensor.  
• The letter next to the hook-up refers to the test procedure for that hook-up.  
• Each hook-up should test O.K. Exception: If two hook-ups are marked with  
an asterisk (*) only one of the two hook-ups has to test O.K. This is neces-  
sary because some sensors look alike, but have different internal connec-  
tions.  
Sensor may be tested on or off vehicle.  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER OFF when  
done.  
3) Disconnect wiring harness from sensor - Inspect for  
damage.  
Some vehicles use a metal snap ring to secure wiring harness  
to sensor. Remove this snap ring before disconnecting wiring  
harness.  
4) Disconnect ductwork from sensor air intake.  
This is so you can operate the sensor element for testing.  
Refer to vehicle service manual for disassembly procedure.  
5) Off-Car testing only: Remove sensor.  
6) Test Preparation is complete. Do tests referenced in  
hook-up diagrams.  
• Test A - Air Flow Meter Sensor (page 2-43)  
• Test B - Air Temperature Sensor (page 2-44)  
• Test C - Air Flow Meter Position Switch (page 2-45)  
2-42  
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Mass Air Flow MAF  
TEST A - Air Flow Meter Sensor  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Do all Test Preparation steps.  
Refer to page 2-42.  
2) Connect test leads.  
• Connect TEST leads according to diagram A in the  
component drawing.  
• Important: If two hook-ups are marked with an asterisk  
(*) only one of the two hook-ups has to test O.K. This is  
necessary because some sensors look alike, but have  
different internal connections.  
3) Verify test clips make good contact and do not touch  
each other.  
HIGH  
Make sure unused clips are not touching anything.  
LOW  
POWER OFF  
4) Set RANGE switch to HIGH.  
RANGE  
VOLTS  
5) Set FUNCTION switch to VOLTS.  
OHMS  
FREQUENCY  
6) Operate sensor - Watch TEST light for results.  
FUNCTION  
Slowly move the sensor element (pivoting “door” or sliding  
cone) back and forth from fully closed to fully open  
position. Use a pencil, or similar object, to push on the  
“door”. This will not harm the sensor.  
Good Sensor - TEST light smoothly moves up or down as  
sensor is operated. (The TEST light may go off if it moves  
to the bottom of the column - this is O.K.) Range of TEST  
light movement varies with sensor type.  
Bad Sensor - TEST light position does not change during  
test OR light movement is erratic, showing a sudden jump  
or dip during smooth sensor operation.  
7) Test A is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads. Reconnect sensor to vehicle if all testing is done.  
2-43  
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Section 2  
Testing Sensors  
TEST B - Air Temperature Sensor  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Do all Test Preparation steps.  
Refer to page 2-42.  
2) Connect test leads.  
Connect TEST leads according to diagram B in the component  
drawing.  
3) Verify test clips make good contact and do not touch each other.  
HIGH  
LOW  
Make sure unused clips are not touching anything.  
POWER OFF  
RANGE  
4) Set RANGE switch to HIGH.  
VOLTS  
5) Set FUNCTION switch to OHMS.  
6) Note TEST light position on tester.  
OHMS  
FREQUENCY  
FUNCTION  
If the sensor is good, the light will move downwards as the sensor  
heats up.  
7) Heat temperature sensor thoroughly.  
• The air temperature sensor is located either...  
– In a small tube extending into the air intake passage in front of  
the closed vane “door” OR  
– In its own housing threaded into the side of the air flow meter  
assembly.  
• Heat sensor using a hair dryer or similar device. DO NOT use a  
match or open flame.  
8) Observe TEST light position for test results.  
Good Sensor - TEST light moved downwards below original position.  
(TEST light may go off if sensor is very hot - this is OK.) The TEST  
light will move upwards as the sensor cools off. Range of TEST  
light movement varies with sensor type and temperature change.  
Bad Sensor - TEST light position did not change during test.  
9) Test B is complete.  
Set RANGE switch to POWER OFF and remove all test leads.  
Reconnect sensor to vehicle if all testing is done.  
2-44  
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Mass Air Flow MAF  
Test C - Air Flow Meter Position Switch  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Do all Test Preparation steps.  
Refer to page 2-42.  
2) Connect test leads.  
Connect TEST leads according to diagram C in the compo-  
nent drawing.  
3) Verify test clips make good contact and do not touch  
each other.  
HIGH  
Make sure unused clips are not touching anything.  
LOW  
POWER OFF  
4) Set RANGE switch to HIGH.  
RANGE  
VOLTS  
5) Set FUNCTION switch to OHMS.  
OHMS  
FREQUENCY  
6) Operate sensor - Watch TEST light for results.  
FUNCTION  
Slowly move the sensor element (pivoting “door” or sliding  
cone) back and forth from fully closed to fully open position.  
Use a pencil, or similar object, to push on the “door”. This will  
not harm the sensor.  
Good Switch - TEST light switches between being  
TEST  
TEST  
ON at top of column and OFF  
Bad Switch - TEST light always ON at top of  
column or always OFF.  
7) Test C is complete.  
Set RANGE switch to POWER OFF and remove all  
test leads. Reconnect sensor to vehicle if all testing  
is done.  
2-45  
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Section 2  
Testing Sensors  
Tooth  
Wire Coil  
Magnet  
Reluctor Ring  
Positive  
Zero  
SENSOR  
VOLTAGE  
S
N
To  
Computer  
Rotation  
Negative  
ROTATION  
Air Gap  
Reluctance Sensor Operation  
Typical Sensor Signal Voltage  
Crankshaft/Camshaft Position sensors  
— The computer needs to know rotational speed (or  
position) of the engine crankshaft/camshaft for controlling  
ignition and fuel injector systems. If the computer is  
handling a Distributorless (or Direct) ignition system or  
controlling the operation of individual fuel injectors, it also  
needs to know when cylinder #1 is active. The sensors have  
various names such as: Crankshaft Position, Crank Angle,  
Flywheel, Distributor Pick-Up, Camshaft Position, Cylinder,  
TDC and RPM.  
What is It  
and  
How is It  
Used?  
— Similar sensors are used in anti-lock brake and electroni-  
cally shifted transmission systems. These sensors have  
names such as: Wheel Speed, Vehicle Speed and  
Driveshaft.  
— The sensors come many styles using different connectors.  
Sometimes an assembly contains more than one sensor.  
Other versions combine two functions into a single sensor  
(usually camshaft position and cylinder #1 identification).  
— The most common sensor types are Magnetic Reluc-  
tance and Hall Effect. These are described below along with  
Optical types which are in limited use.  
• Magnetic  
Reluctance  
The basic reluctance sensor consists of a permanent  
magnet with a coil of wire wrapped around it. Nearby the  
sensor is a toothed ring made of iron or steel (sometimes  
called a “reluctor”). The ring is attached to a rotating  
component such as the crankshaft or camshaft. Whenever  
a tooth from the ring passes by the sensor, it attracts the  
magnetic field lines surrounding the magnet. As the field  
lines move, they pass through the wire coil and generate a  
small voltage pulse (magnetic induction principle). Thus a  
voltage pulse is generated every time a tooth passes by  
the sensor coil.  
2-46  
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Crankshaft/Camshaft Position  
HIGH  
SHUTTER  
SIGNAL  
VOLTAGE  
HALL  
SWITCH  
POWER  
GROUND  
SIGNAL  
MAGNET  
LOW  
ROTATION  
Typical Hall Effect Sensor  
Typical Sensor Signal Voltage  
The computer determines rotational speed (or position) by  
measuring how fast (or when) pulses appear. Note: The  
voltage pulses get larger when the teeth pass by more  
quickly. Values can range from a fraction of a volt (crank  
RPM) to over a hundred volts (high RPM).  
• Hall Effect The basic Hall effect sensor consists of a permanent  
magnet and a small module containing a transistorized Hall  
effect switch. (Power and ground connections are required  
for operation.) A small air gap separates the sensor and the  
magnet. The magnetic field causes the Hall switch to turn  
on and send out a low voltage signal. If a metal strip (iron or  
steel) is placed in the gap, it blocks the magnetic field from  
reaching the Hall device. This causes the Hall switch to turn  
off and send a high voltage signal out on the signal wire.  
The metal strips (blades) are part of a disk or cup attached  
to a rotating component such as the crankshaft or camshaft.  
As the blades pass through the sensor gap, the voltage  
signal switches high and low creating a series of pulses.  
The computer determines rotational speed (or position) by  
measuring how fast (or when) pulses appear.  
• Optical  
The optical crank angle sensor consists of a light  
source, a light detector (photo-electric cell) and a rotor  
plate, which is a slotted disk. Since the distributor shaft  
and/or camshaft are linked to the rotor plate, they  
move together. As the rotor plate rotates, the slits on  
the disk interrupt a beam or light sent by the light  
source to the light detector. This interrupting action  
creates two pulse waveforms that are monitored by the  
engine computer. The engine computer uses these  
waveforms and other engine sensors to optimally  
control ignition timing.  
2-47  
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Section 2  
Testing Sensors  
— Crankshaft Position, Crank Angle, Flywheel, Distributor  
Pick-Up, Camshaft Position, Cylinder, TDC and RPM. The  
sensor is usually located inside the distributor (if the  
engine has one). Vehicles without a distributor have the  
sensor located in various places around the engine where  
it can be mechanically linked to the crankshaft or camshaft.  
Where is  
It?  
— Driveshaft: Sensor located in transmission housing or  
near driveshaft.  
— Wheel Speed, Vehicle Speed: Sensors on individual  
wheels, drive shaft, or transmission shaft.  
• Related trouble codes sent by computer.  
When to  
Test  
• Problems with...  
– Ignition: No start, stalling, rough running.  
– Electronic Transmission: No torque converter lock-up,  
faulty shifting or slipping.  
– ABS system: Faulty or not working.  
All Sensor Types: Sensor operation (see tests on page 2-  
49 through 2-52). Poor connections at sensor or computer.  
Faulty sensor wiring (open or short circuits).  
What to  
Inspect  
– Magnetic Reluctance: Too much gap between sensor  
coil and reluctor ring. Cracked, broken, or missing teeth on  
reluctor ring. Note: Some rings may normally have a gap  
or irregular tooth space. This gives the computer cylinder  
identification information.  
– Hall Effect: Foreign objects in gap between Hall sensor  
and shutter assembly. Cracked, broken, or missing blades  
on shutter. Note: Some shutter assemblies may normally  
have irregular blade spacing. This gives the computer  
cylinder identification information.  
– Optical: Dirt in the rotor blade slots or light source/  
detector assembly. Broken or worn teeth on the distributor  
shaft (if used) or sensor shaft.  
2-48  
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Crankshaft/Camshaft Position  
Test A - Magnetic Reluctance Type Sensor  
Testing is done on-vehicle.  
DO NOT test vehicle speed or driveshaft type sensors since they require  
vehicle motion.  
Warning: Observe all safety precautions (see page ii) when testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Disconnect wiring harness from sensor - Inspect  
for damage.  
Some vehicles use a metal snap ring to secure  
wiring harness to sensor. Remove this snap ring  
before disconnecting wiring harness.  
4) Connect test leads.  
Refer to vehicle service manual for sensor pin  
identification. Some connectors handle more than  
one sensor. Test all sensors.  
• YELLOW to one end of sensor coil pin.  
• BLACK to other end of sensor coil pin.  
5) Verify test clips make good contact and do not  
touch each other.  
HIGH  
Make sure unused clips are not touching anything.  
LOW  
POWER OFF  
6) Set RANGE switch to LOW.  
RANGE  
VOLTS  
7) Set FUNCTION switch to VOLTS.  
OHMS  
FREQUENCY  
8) Operate sensor - Watch TEST light for results.  
FUNCTION  
(Note: Ignore any RICH / LEAN light flashes.)  
– Crankshaft/Camshaft sensor: Crank engine.  
STAY AWAY from moving engine parts.  
2-49  
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Section 2  
Testing Sensors  
Observe all safety precautions (see page ii) - engine  
may start or backfire.  
Note: Some computer systems will store a trouble  
code in memory (and turn on the “Check Engine”  
light) if engine is cranked with sensor disconnected.  
Ignore or erase the code after testing. Refer to  
vehicle service manual.  
– Wheel Speed sensor: Raise wheel off ground. Use  
jack stands and observe all safety precautions (see  
page ii). Give the wheel a quick spin in either  
direction to test.  
TEST  
Good sensor - TEST lights flicker or stay ON during  
testing. Position and range of TEST light activity  
varies with sensor type.  
Bad sensor - TEST lights OFF during testing.  
9) Testing is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads.  
2-50  
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Crankshaft/Camshaft Position  
Test B - Hall Effect Type or Optical Type Sensor  
Sensor may be tested on or off vehicle.  
Warning: Observe all safety precautions (see page ii) if testing sensor on  
vehicle.  
1) Verify ignition key is OFF.  
2) Check Tester battery  
Refer to page 1-4. Set RANGE switch to POWER  
OFF when done.  
3) Disconnect wiring harness from sensor - Inspect  
for damage.  
Some vehicles use a metal snap ring to secure  
wiring harness to sensor. Remove this snap ring  
before disconnecting wiring harness.  
4) Off-Car testing only: Remove sensor.  
5) Connect test leads.  
Refer to vehicle service manual for sensor pin  
identification. Some connectors handle more than  
one sensor. Test all sensors.  
• RED to sensor power pin.  
• YELLOW to sensor signal pin.  
• BLACK to sensor ground pin.  
6) Verify test clips make good contact and do not  
touch each other.  
HIGH  
LOW  
Make sure unused clips are not touching anything.  
POWER OFF  
RANGE  
7) Set RANGE switch to LOW.  
VOLTS  
8) Set FUNCTION switch to FREQUENCY.  
OHMS  
FREQUENCY  
9) Operate sensor - Watch PULSE light for  
FUNCTION  
results.  
(Note: Ignore any TEST light action.)  
2-51  
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Section 2  
Testing Sensors  
On-Car test: Crank engine. STAY AWAY from moving  
engine parts. Observe all safety precautions (see  
page ii) - engine may start or backfire.  
Good sensor - PULSE light flashes or stays ON  
PULSE  
during cranking (varies with sensor type).  
Bad sensor - PULSE light OFF during cranking.  
Note: Some computer systems will store a trouble code  
in memory (and turn on the “Check Engine” light) if  
engine is cranked with sensor disconnected. Ignore or  
erase the code after testing. Refer to vehicle service  
manual.  
Off-Car test: Slide a flat piece of iron or steel in and  
out of the sensor slot. Use a scrap piece of sheet  
metal, knife blade, steel ruler or similar.  
Good sensor - Single flash on PULSE light whenever  
metal is moved in and out of slot. (The flash will  
occur either when the metal enters the slot or when  
it is removed - depends upon sensor.)  
Bad sensor - PULSE light OFF during testing.  
10) Testing is complete.  
Set RANGE switch to POWER OFF and remove all test  
leads.  
Red  
Red  
Yellow  
Black  
Chrysler Distributor  
Yellow  
Black  
Hall Effect  
Ford Distributor Hall Effect  
(PIP Sensor, TFI-IV Ignition  
2-52  
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Section  
Testing  
3
Ignition Modules  
Save yourself time! Always begin with a thorough  
visual and “hands-on” inspection. You can often  
find the cause of many problems by just looking.  
Troubleshooting  
Tips  
Has the vehicle been serviced recently? Some-  
times things get reconnected to the wrong place,  
or not at all.  
Poor grounding can cause no-starts! Some  
modules make ground connections to vehicle  
chassis. Check mounting hardware, module  
flanges and chassis for clean contact surfaces and  
snug attachment.  
• Inspect wiring for:  
– Contact with sharp edges.  
– Contact with hot surfaces, such as exhaust  
manifolds.  
– Pinched, burned or chafed insulation.  
– Proper routing and connections.  
• Check electrical connectors for:  
– Corrosion on pins.  
– Bent or damaged pins.  
– Contacts not properly seated in housing.  
– Bad wire crimps to terminals.  
• Check crankshaft/camshaft sensors connected  
to ignition module. (Refer to page 2-46.)  
• Many ignition modules require heat transfer  
grease applied between module and mounting  
surface. Modules can overheat and fail if  
grease is missing or incorrectly applied.  
3-1  
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Section 3  
Testing Ignition Modules  
Ignition Module Test Procedure  
GM • Ford • Chrysler • Toyota • Honda • Nissan  
Important:  
• This test checks for “dead” modules causing a no-start. This test will not  
detect intermittent failures due to heat or engine vibration.  
• Refer to vehicle service manual for module location, removal and installa-  
tion procedures.  
– Module access may require distributor removal. Follow service manual  
procedures  
– Check ignition timing with a timing light when the distributor is reinstalled.  
• Always check the 9 volt battery in the tester (refer to page 1-4).  
1) Locate module diagram on proceding pages.  
2) Connect test leads as shown.  
Begin with the Test 1 hook-up if more than one  
test is shown.  
Always make sure metal clips make good contact  
HIGH  
LOW  
and do not touch each other.  
POWER OFF  
RANGE  
3) Set RANGE switch to LOW.  
VOLTS  
4) Set FUNCTION switch to FREQUENCY.  
OHMS  
FREQUENCY  
5) Observe PULSE light for test results.  
FUNCTION  
• Flashing light means good module. (There may  
be a short delay before flashing starts.)  
PULSE  
• No flashing means bad module.  
Note: The bottom TEST lights may also flash.  
This is normal and may be ignored.  
Exception: When testing “ring” type modules  
(lower half, page 3-11), spin the distributor shaft  
to activate the PULSE light. (Light on or flashing  
during spin means good module.)  
3-2  
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IGNITION MODULES  
GM 7 & 8 pin modules only:  
– Reconnect test leads as shown in Test 2  
diagram.  
– Observe PULSE light. It should NOT be  
flashing. If PULSE light flashes, module is bad.  
– Short pins E and R together using paper clip (or  
other metal jumper).  
– Observe PULSE light for test results.  
• Flashing light means good module. (There may  
be a short delay before flashing starts.)  
• No flashing means bad module.  
Ford modules with two test hook-ups:  
– Reconnect test leads as shown for Test 2. (Only  
the Green test lead is moved.)  
– Observe PULSE light for test results.  
• Flashing light means good module. (There may  
be a short delay before flashing starts.)  
• No flashing means bad module.  
6) Testing is complete.  
Set RANGE switch to POWER OFF and remove all  
test leads.  
3-3  
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Section 3  
Testing Ignition Modules  
GM  
4 and 5 pin  
Black  
*
Yellow  
Red  
Green  
Test clip must  
touch both base  
plate and bushing  
BUSHING  
BASE  
*
PLATE  
Black  
*
Yellow  
Red  
Green  
3-4  
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GM  
7 pin  
Test 1  
Black  
Black  
*
*
Yellow  
Red  
Green  
Yellow  
Red  
Green  
Test clip must  
touch both base  
plate and bushing  
*
Black  
Test 2  
BUSHING  
*
BASE  
PLATE  
Black  
Yellow  
Red  
Green  
Blue Jumper  
*
Yellow  
Red  
Green  
Blue Jumper  
3-5  
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Section 3  
Testing Ignition Modules  
GM  
Green  
8 pin  
P
N
SIDE  
VIEW  
Test 1  
+C  
GBRE  
END  
C
G
B
R
E
VIEW  
Black  
Red  
Yellow  
Green  
P
N
SIDE  
VIEW  
Test 2  
+C  
GBRE  
C
G
B
R
E
END  
Red  
VIEW  
Black  
Yellow  
Blue Jumper  
3-6  
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Ford  
Dura-Spark  
Blue Jumper  
Red  
Note: Dura-Spark  
ignition modules  
come in several  
White  
Red  
versions with different  
connector types.  
Black  
(or Black/Green)  
Black  
MODULE  
Make connections  
based on ignition  
module wire colors.  
Other module wires  
not used for testing.  
Yellow  
Green  
Green  
Orange  
Ford  
TFI  
Blue Jumper  
Black  
Green  
4
5
6
3
2
1
Red  
SIDE  
VIEW  
Yellow  
END  
VIEW  
3-7  
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Section 3  
Testing Ignition Modules  
Ford  
TFI-IV  
Test 1: Connect leads as shown.  
Test 2: Move Green lead to pin 5.  
Other leads remain in original position  
Black  
Green  
7
8
9
6
5
4
3
2
1
Red  
Yellow  
SIDE  
VIEW  
END  
VIEW  
Ford  
TFI-IV  
Test 1: Connect leads as shown.  
Test 2: Move Green lead to pin 5.  
Other leads remain in original position  
Green  
Red  
Yellow  
SIDE  
VIEW  
END  
VIEW  
Black  
3-8  
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Chrysler  
5-pin type shown.  
4 and 5 pin  
4-pin uses same hook-up.  
Black  
Red  
1
Yellow  
2
4
3
5
Green  
Magetic Reluctance Pick-up  
Yellow  
5
1
2
Black  
4
3
Green  
Red  
Hall Effect Pick-up  
3-9  
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Section 3  
Testing Ignition Modules  
Honda  
3
2
4
1
Black  
Green  
Red  
1
Red  
Yellow  
Red  
Green  
Green  
Yellow  
Yellow  
3
2
3
2
1
4
4
Black  
Connect BLACK test lead  
to igniter mounting holes  
or a metal ground inside  
distributor.  
3-10  
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Honda/Nissan  
Yellow  
Red  
Bushing  
Green  
Base plate  
Black  
Not present on  
some modules.  
Test clip must touch both  
base plate and bushing  
IMPORTANT  
Red  
1) Remove distributor from  
engine before testing.  
Yellow  
2) Module remains inside  
distributor during test.  
Black  
Red  
Yellow  
Connect BLACK test lead  
to a good ground inside  
distributor.  
Black  
E
B
I
Connect BLACK test lead  
to a good ground inside  
distributor.  
Red  
Yellow  
Black  
E
B
C
I
Connect BLACK test lead  
to a good ground inside  
distributor.  
3-11  
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Section 3  
Testing Ignition Modules  
Nissan  
Test clip must touch both  
base plate and bushing  
Bushing  
Base plate  
S
B
E
I
Black  
Yellow  
Pick-up pins  
Green  
Red  
Nissan  
1987-1989 300ZX only  
One-Coil System  
(Photo pick-up)  
Nissan uses two types  
*
of connector wiring.  
Module is good if either  
hook-up tests O.K.  
Yellow  
Green  
Black  
*
*
OR  
Green  
Yellow  
Yellow  
Yellow  
Green  
Black  
Black  
Black  
*
*
1
2
4
3
1
2
4
3
OR  
Green  
Yellow  
Green  
Black  
3-12  
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Nissan  
Two-Coil System  
(Photo pick-up)  
Yellow  
Green  
Black  
Nissan uses two types  
of connector wiring.  
Module is good if either  
hook-up tests O.K.  
*
Yellow  
Black  
Black  
*
*
1
2
4
1
2
4
3
OR  
3
Green  
Yellow  
Green  
Green  
Yellow  
Black  
Not present on  
some modules.  
3-13  
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Section 3  
Testing Ignition Modules  
Toyota  
Yellow  
Use a paper clip to  
connect test lead.  
Green  
Red  
Black  
Connect BLACK test  
lead to igniter mounting  
hole or good vehicle  
ground.  
IMPORTANT  
For Toyota modules not pictured, refer to  
vehicle service manual and connect as follows:  
• Red lead to battery pin  
• Yellow lead to coil pin  
• Black lead to module ground  
• Green lead to IGT pin  
3-14  
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Toyota  
Green  
Red  
BROWN  
BLACK  
Yellow  
Black  
Connect  
BLACK test  
lead to igniter  
mounting hole  
or good vehicle  
ground.  
C
Ext  
B
I,T  
F
Green  
Yellow  
Red  
3-15  
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Section 3  
Testing Ignition Modules  
Toyota  
Green  
Red  
Yellow  
Yellow  
Use a paper clip to  
connect test lead.  
Black  
Connect  
BLACK test  
lead to igniter  
mounting hole  
or good vehicle  
ground.  
Green  
3-16  
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Toyota  
Green  
Black  
Connect  
BLACK test  
Red  
lead to igniter  
mounting hole  
or good vehicle  
ground.  
Yellow  
Use a paper clip to  
connect test lead.  
3-17  
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Section 3  
Testing Ignition Modules  
Toyota  
Black  
Connect BLACK  
test lead to igniter  
mounting hole or  
good vehicle  
ground.  
Green  
Red  
Yellow  
Use a paper clip to  
connect test leads.  
3-18  
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Toyota  
Yellow  
Red  
Green  
Green  
Yellow  
Red  
Black  
Connect BLACK  
test lead to igniter  
mounting hole or  
good vehicle  
ground.  
3-19  
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Section 3  
Testing Ignition Modules  
Toyota  
Yellow  
Red  
Green  
Black  
Connect  
BLACK test  
lead to igniter  
mounting hole  
or good vehicle  
ground.  
3-20  
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Toyota  
Red  
Red  
Green  
Green  
+
B
SG  
+
B
SG  
C
C
Yellow  
Red  
Yellow  
Green  
Red  
Yellow  
Yellow  
Green  
Connect BLACK test lead  
to igniter mounting holes.  
Black  
3-21  
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Notes  
3-22  
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Section  
More Uses for the  
Ignition Module &  
Engine Sensor Tester  
4
Circuit Voltage Checks  
This function is useful for checking the presence (or absence) of voltages  
throughout the vehicle electrical system (such as wiring, switches, relays, and  
connectors). It is safe for probing computer and sensor circuits.  
Warning: Observe all safety precautions when working on vehicles (see page ii).  
HIGH  
LOW  
POWER OFF  
1) Set FUNCTION switch to VOLTS.  
2) Set RANGE switch to HIGH.  
RANGE  
VOLTS  
OHMS  
3) Connect BLACK test lead to circuit ground.  
4) Probe with YELLOW test lead.  
FREQUENCY  
FUNCTION  
Warning: Do not connect to secondary ignition  
circuits - dangerous voltages present!  
VOLTS  
TEST  
5) TEST light position indicates measured voltage.  
Each light represents a 0.5 volt step along a  
span of 0.5 to 5 volts.  
over5  
4.5  
4
• Top TEST light ON - voltage is 5 volts, or  
higher.  
3.5  
3
• Other TEST lights ON - see illustration for  
voltage level.  
2.5  
2
• All TEST lights OFF - voltage is less than 0.5  
volts, not present or negative polarity.  
1.5  
1
Important:  
• Always make sure all connections are good at  
the contact points.  
.5  
• Negative voltages, no matter how large, will  
NOT turn on TEST lights.  
• More than one TEST light on, or jumping  
around, means the measured voltage is  
erratic or rapidly changing.  
4-1  
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Section 4  
Continuity Checks  
Test wiring, ground connections, switch operation, relay contacts, or similar.  
Important:  
• Do continuity tests on unpowered circuits only.  
• Always make sure all connections are good. If necessary, scrape away  
corrosion, paint, etc. at the contact points.  
Warning: If working on-car, turn ignition key OFF and observe all safety  
precautions (see page ii).  
HIGH  
LOW  
1) Set RANGE switch to HIGH.  
POWER OFF  
RANGE  
2) Set FUNCTION switch to OHMS.  
VOLTS  
3) Connect YELLOW test lead to one end of circuit (such as  
OHMS  
FREQUENCY  
wire, switch or relay contact).  
FUNCTION  
4) Connect BLACK test lead to other end of wire, switch or  
relay.  
5) TEST light position indicates  
amount of continuity.  
Yellow  
Black  
Yellow  
Black  
• All TEST lights OFF - Short Circuit  
(measured resistance is 200 ohms,  
or less).  
TEST  
TEST  
• Top TEST light ON - Open Circuit  
(measured resistance is 7 Kohms,  
or higher).  
Short  
circuit  
Open  
circuit  
Other TEST lights ON mean circuit has  
resistance between 200 ohms and 7 K  
ohms.  
Low Resistance Checks  
• RANGE switch on LOW.  
HIGH  
LOW  
POWER OFF  
RANGE  
• FUNCTION switch on OHMS.  
VOLTS  
• Use YELLOW and BLACK test leads.  
OHMS  
FREQUENCY  
All TEST lights OFF - resistance is 30 ohms, or less.  
Top TEST light ON - resistance is 300 ohms, or higher.  
FUNCTION  
Other TEST lights ON mean resistance is between 30 ohms and  
300 ohms.  
4-2  
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More Uses for the Ignition Module/Sensor Tester  
Continuity Checks (cont.)  
Yellow  
Black  
Yellow  
Black  
TEST  
TEST  
Switch  
Closed  
Switch  
Open  
Yellow  
Black  
Yellow  
Black  
12V  
12V  
TEST  
TEST  
Ground  
Connection  
No  
Ground  
Connection  
4-3  
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Section 4  
Diode Checks  
Tests diodes and rectifiers for proper operation.  
HIGH  
LOW  
1) Set RANGE switch to HIGH.  
POWER OFF  
RANGE  
2) Set FUNCTION switch to OHMS.  
VOLTS  
OHMS  
3) Connect TEST leads as shown in Figure 1.  
FREQUENCY  
FUNCTION  
( YELLOW to anode — BLACK to cathode)  
4) The bottom TEST light should be ON. If a  
different TEST light is on or all lights are off, the  
diode is defective.  
5) Reverse test lead connections as shown in  
Figure 2.  
( YELLOW to cathode — BLACK to anode)  
6) The top TEST light should be ON. If a different  
TEST light is on or all lights are off, the diode is  
defective.  
Note: Always make sure all connections are good. If  
necessary, scrape away corrosion, paint, etc. at the  
contact points.  
Yellow  
Black  
Black  
Yellow  
TEST  
TEST  
Fig. 1  
Fig. 2  
4-4  
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Warranty  
(Garantia)  
FULL ONE (1) YEAR WARRANTY  
Actron Manufacturing Company, 9999 Walford Avenue, Cleveland, Ohio 44102-  
4621, USA warrants to the user that this unit will be free of defects in materials and  
workmanship for a period of one (1) year from the date of original purchase. Any unit  
that fails within this period will be repaired without charge when returned to an  
authorized factory repair center. Actron requests that a copy of the original, dated  
sales receipt be returned with the unit to determine if the warranty period is still in  
effect. This warranty does not apply to damages caused by accident, alterations or  
improper or unreasonable use. Expendable items, such as batteries, fuses, lamp  
bulbs and flash tubes are also excluded from the scope of this warranty. Actron  
Manufacturing Company disclaims any liability for incidental or consequential dam-  
ages for breach of any written warranty on the unit. Some states do not allow the  
disclaimer of liability for incidental or consequential damages, so the above dis-  
claimer may not apply to you. This warranty gives you specific legal rights and you  
may also have rights which vary from state to state.  
All information, illustrations and specifications contained in this manual are based on  
the latest information available from industry sources at the time of publication. No  
warranty (expressed or implied) can be made for its accuracy or completeness, nor  
is any responsibility assumed by Actron Manufacturing Company or anyone con-  
nected with it for loss or damages suffered through reliance on any information  
contained in this manual or misuse of the accompanying product. Actron Manufac-  
turing Company reserves the right to make changes at any time to this manual or  
accompanying product without obligation to notify any person or organization of such  
changes.  
Customer Service Centers  
Actron Manufacturing  
Company  
9999 Walford Avenue  
Cleveland, Ohio 44102-4621  
USA  
Actron - Europe  
Coppen Road, Dagenham,  
Essex RM8 1NU  
Actron - Europe  
60 Rte de St Gemme  
78860 St NOM LA BRETECHE  
FRANCE  
UNITED KINGDOM  
Tel: +33-1-30802205  
Fax: +33-1 30802182  
Tel: +44-(0)181-984-8855  
Fax: +44-(0)181-984-8866  
Tel: +1-261-651-9200  
Fax: +1-216-651-2853  
Product Information Only  
Product Information & Repair  
Product Information & Repair  
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®
Made in the U.S.A.  
Part No. 2-221301  
Actron Manufacturing Company  
9999 Walford Avenue  
Cleveland, Ohio 44102-4696  
©1997, Actron Manufacturing Company  
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