Actron CP9087 User Manual

TEST

IGNITION MODULE &

ENGINE SENSOR TESTER

HIGH

RANGE

RICH

Select

LOW

LOW,

POWER OFF

VOLTS

VOLTS

OHMS

FREQUENCY

FUNCTION

9V BATTERY TEST: 1) SET RANGE TO HIGH.

SIGNAL COMMON TRIGGER POWER 9V

2) SET FUNCTION TO OHMS. 3) DISCONNECT ALL LEADS.

O.K. IF TOPMOST TEST LIGHT IS ON. WEAK IF ANOTHER LIGHT IS ON.

®

LEAN

PULSE

CP9087

PROFESSIONAL

TM

Vehicle
Service

Info

The following publishers have manuals containing diagnostic information for
electronic engine control and ignition systems. Contact the publishers for
availability and pricing, specifying the make, model and year of your vehicle.
Some manuals may be available at auto parts stores or your local public library.

Vehicle Service Manuals

Chilton Book Company

Chilton Way
Radnor, PA 19089

Haynes Publications

861 Lawrence Drive
Newbury Park, CA 91320

Vehicle Service
Manuals from General
Motors Corporation

Buick, Cadillac,
Chevrolet, GEO, GMC,
Oldsmobile & Pontiac

Helm Incorporated
Post Office Box 07130
Detroit, MI 48207

Saturn

Adistra Corporation
c/o Saturn Publications
101 Union Street

Post Office Box 1000
Plymouth, MI 48170

Cordura Publications

Mitchell Manuals, Inc.
Post Office Box 26260
San Diego, CA 92126

Suitable manuals have titles such as:
“Electronic Engine Controls”
“Fuel Injection and Feedback Carburetors”
“Fuel Injection and Electronic Engine Controls”
“Emissions Control Manual”
... or similar titles.

Vehicle Service
Manuals from Ford
Motor Company (Ford,

Motor’s Auto Repair Manual

Hearst Company
250 W. 55th Street
New York, NY 10019

Vehicle Service
Manuals from Toyota,
Honda, Nissan

Lincoln, Mercury)

Ford Publication Dept.
Helm Incorporated
Post Office Box 07150
Detroit, MI 48207

Vehicle Service
Manuals from Chrysler
Corporation

Chrysler Corporation
Dyment Distribution Service
Post Office Box 360450
Strongsville, OH 44136

Toyota Motor Corporation
Toyota Service Publications
750 W. Victoria Street
Compton, CA 90220-5538

Honda Motor Co., Ltd.
Helm Incorporated
Post Office Box 07280
Detroit, MI 48207

Nissan North America, Inc.
Dyment Distribution Service
c/o Nissan
20770 Westwood Drive
Strongsville, OH 44136

Index

Section

1
2

3
4

Vehicle Service Information ...................... Inside front cover

Safety Precautions ............................................................... ii

Tester Basics............................................. 1-1

Testing Sensors ..........................................

• 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

More Uses for the Sensor Probe ...............4-1

• "Circuit Tester" Voltage Check ........................... 4-1

• Continuity Checks ............................................... 4-2

• Diode Check........................................................ 4-4

2-1

i

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 unexpect­edly, 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 discon­nected) because of a special energy reserve module.

• Always follow vehicle manufacturer’s warnings, cautions, and service procedures.

ii

6-3

Section

Tester

1

— 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).

RANGE

Switch

Basics

Controls power to the Tester and selects measure-

1

ment range sensitivity (as required by various
sensor tests).

• 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.

2

FUNCTION

Switch

Selects the type of signal being measured (for
conducting sensor and ignition module tests). Different
kinds of signals are used by various sensors.

• VOLTS - Measures voltages. This function is used
to test most sensors.

• 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

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

Lights

PULSE

Light

RICH/
LEAN

Lights

TEST light is off or near the bottom of the column. The TEST light
moves higher up the column as the signal level increases.

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

4

if the module is good.
Note that the PULSE light will also be on (or flash) whenever

frequency signals are being measured - this is normal.

These lights are active when the tester switches are set to LOW

5

VOLTS only.

• LEAN (green): ON for voltages between 0.1 and 0.59 volts.

• RICH (red): ON for voltages above 0.6 volts.

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.

1-2

6

6

Test

Leads

Two or more of these are used for the various tests and checks.
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.

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.

IGNITION MODULE &

IGNITION MODULE &

ENGINE SENSOR TESTER

ENGINE SENSOR TESTER

TEST

Tester Bas ics

6

1

2
4

7

Backprobe

Adapter

To Sensor

3

5

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

Select
LOW,
VOLTS

PULSE

RICH

LEAN

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.

• 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)

• Grasp open end of adapter with test lead clip. Keep
pushing on adapter to maintain circuit contact.

To Computer

Caution: The “scooped” end of the
adapter will break if you bend it.

1-3

Section 1

8

Jumper Lead

9

Connector

Pin Adapters

Tester Basics

Used when checking some ignition modules. Makes
extra connections as required for testing.

Used for easier attachment of test leads to certain
sensor or wiring connector pins.

• Push one end of the adapter onto the desired

connector pin.

• Grasp the other end with the test lead clip.

9V

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

Sensor

Tester
Power

TEST

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).

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.

2. Set RANGE switch to HIGH.

3. Set FUNCTION switch to OHMS.

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.

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

Section 2

Section

2

T roubleshooting

Tips

HVAC

YST

CE BOOSTER

G GAP

U.S.A.

M

CRUISE

EGR
VAC
REG

EGR
VAC
REG

BRAKE BOOSTER

FUEL
PRESS
REG.

TO TRANS

MODE

FRONT

OF CAR

12RA C8

6DLC24

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.

• 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:
– Correct routing. Refer to vehicle service

manual, or Vehicle Emission Control Information
(VECI) decal located in the engine compartment.

– Pinches and kinks.
– 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.

5AAC28

• Check electrical connectors for:
– Corrosion on pins.
– Bent or damaged pins.
– Contacts not properly seated in housing.
– Bad wire crimps to terminals.

2-1

Section 2

Typical Engine Coolant

Temperature Sensor

Engine TEMPERA TURE

HIGH

SENSOR
RESISTANCE

LOW

Cold Hot

TEMPERATURE

What is It?

How is It

Used?

Location

When to Test

The engine 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. (Exception: some Chrysler engines
have a dual sensor with three wires.)

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).

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.

• Driveability problems such as hard starting,
rough idle, stalling, hesitation, stumble, surging,
knocking (pinging), poor fuel economy, or black
exhaust smoke.

2-2

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).

Air TEMPERA TURE

HIGH

SENSOR
RESISTANCE

LOW

Typical Air Temperature Sensor

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.

Cold Hot

TEMPERATURE

How is It

Used?

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.

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

What to

Inspect

• 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).

2-3

Section 2

Testing Sensor s

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 tempera­ture 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.

2-4

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.

Be careful of coolant spillage from mounting hole if
removing engine temperature sensor.

5) Connect test leads.

• YELLOW to

• BLACK to remaining sensor pin.

Yellow

either sensor pin.

Black

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

Engine Air TEMPERA TURE

6) Verify test clips make good contact and do not touch each
other.

Make sure red and green test clips are not touching anything.

7) Set RANGE switch to HIGH.

8) Set FUNCTION switch to OHMS.

9) Note TEST light position on tester.

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

Section 2

TYPICAL THROTTLE POSITION SENSORS

Testing Sensor s

HIGH

2-6

What
is It?

Throttle Position Sensor

The throttle position sensor is a
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
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.

SIGNAL

VOLTAGE

LOW

ROTATION

MAX.MIN.

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.

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.)

How it is

used?

Location

When to

Test

What to

Inspect

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.

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.

• 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.

2-7

Section 2

Testing Sensor s

Throttle Position Sensor Connectors

= Test A, page 2-10

A

= Test B, page 2-12

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

Red

Yellow

Black

GM, FORD, CHRYSLER, HONDA

Black

Yellow

Red

Some sensors require more than one test.

Black

A

A

Yellow

Red

Yellow

Red

Black

A

FORD

A

2-8

HONDA

Yellow

RedBlack

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

HONDA

RedBlack

Yellow

HONDA

AA A

RedBlack

Yellow

THROTTLE POSITION Sensor/Switch

A

B

TOYOTA

A

TOYOTA/NISSAN

B

BlackYellowRed

BlackYellow

Yellow Black

B

Black Yellow

Not used on some
vehicles. Perform this
test only if vehicle
mating connector has

3 wires.

Red

Yellow

Black

Some sensors have
cable attached here.
Testing is identical.

Black
Yellow

B B

Yellow
Black

Not used on some
vehicles. Perform
this test only if
vehicle mating
connector
has 3 wires.

2-9

Section 2

Testing Sensor s

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.

2-10

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 compo­nent drawing.

6) Verify test clips make good contact and do not touch
each other.

Make sure unused clips are not touching anything.

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
throttle closure speed so engine will not stall.

8) Set RANGE switch to HIGH.

9) Set FUNCTION switch to VOLTS.

10) Operate sensor - Watch TEST light for results.

(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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

• 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

Section 2

Testing Sensor s

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 disconnect­ing wiring harness.

2-12

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 compo­nent drawing.

6) Verify test clips make good contact and do not touch
each other.

Make sure unused clips are not touching anything.

THROTTLE POSITION Sensor/Switch

HIGH
LOW

RANGE

FUNCTION

POWER OFF

VOLTS
OHMS
FREQUENCY

7) Set RANGE switch to HIGH.

8) Set FUNCTION switch to OHMS.

9) Operate sensor - Watch TEST light for results.

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.

TEST TEST

• Good Switch

- TEST light switches between

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

Section 2

Testing Sensor s

FORD

EGR Valve

HONDA

EGR Valve

What is it? This sensor is a potentiometer - a type of variable

HIGH

SENSOR

VOLTAGE

LOW

VALVE OPENING

resistor (similar to a dashboard light dimmer
control). The computer supplies power and ground
to the sensor. the sensor has a shaft which is
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.

MAX.MIN.

How it is

Location Attached to the top of the EGR valve.

When to Test

2-14

used?

What to

Inspect

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.

• Related trouble codes sent by computer.

• 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 connec­tions 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.

EGR Valv e Pos ition/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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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.

7) Set RANGE switch to HIGH.

8) Set FUNCTION switch to VOLTS.

9) Operate sensor - Watch TEST light for results.

(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

Section 2

Off-Car test: Slowly push sensor element back and forth
from end to end.

• Good Sensor

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 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.

Testing Sensor s

- TEST light smoothly moves up or down as

- TEST light position does not change during

2-16

EGR Valv e Pos ition/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

RedYellow

Black

HONDA – #2HONDA – #1

Yellow

Red

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

Yellow Red

Black

Honda uses two
sensor types. Try
hook-up #1 first.
If good test
results are not
obtained, retest
using hook-up #2
before judging
sensor.

2-17

Section 2

Testing Sensor s

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).

2-18

How it is

used?

Location

The sensor must be very hot to operate: 349(C
(660(F). Many have 2-wire heating elements built­in 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
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.

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.

Inspection

IMPORTANT:

Sensor operation (see page 2-21). Poor connec­tions at the sensor or computer.

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.

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

Section 2

Testing Sensor s

Sensor Types

1-Wire: Single wire goes to sensor SIGNAL.
Sensor housing is connected to sensor GROUND.

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 identifica­tion. (Signal wire is often black.)

2-20

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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

TEST

5) Verify test clips make good contact and do not touch each
other.

Make sure unused clips are not touching anything.

6) Set RANGE switch to HIGH.

7) Set FUNCTION switch to OHMS.

8) Observe TEST light for test results.

• Good Heater:

• Bad Heater:

TEST light OFF (low resistance).

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

Section 2

Testing Sensor s

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.

2-22

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

4) Verify test clips make good contact.

Make sure unused clips are not touching anything.

5) Set RANGE switch to LOW.

6) Set FUNCTION switch to VOLTS.

7) Start engine - Idle until hot.

Run engine until upper radiator hose is hot and
pressurized.

RICH

LEAN

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

LEAN

– 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.

– 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

Section 2

Testing Sensor s

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.

2-24

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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.

Make sure unused clips are not touching anything.

8) Set RANGE switch to LOW.

9) Set FUNCTION switch to VOLTS.

10) Light torch - Heat sensor tip - Observe RICH/
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.

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:

seconds indicating a “rich” (low oxygen) condition.

– Bad Sensor:

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:

seconds indicating a “lean” (high oxygen) condition.

– Bad Sensor:

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 light turns ON within 3

RICH light takes longer than 3

LEAN light turns ON within 3

LEAN light takes longer than 3

RICH

LEAN

Fig. 1 Fig. 2

RICH

LEAN

2-25

Section 2

Yellow

Black

Testing Sensor s

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.

Yellow

Black

How it is

used?

The computer (or other spark timing controller) is
designed to recognize sensor signals caused by
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 perfor­mance and fuel economy (excess spark retard).

What to

Inspect

2-26

Sensor operation (see test on page 2-27). Poor
connections at sensor or computer. Faulty sensor
wiring (open or short circuits). Spark timing. Bad
fuel quality.

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:

• YELLOW test lead to either sensor pin.

• BLACK test lead to remaining sensor pin.

5) Set RANGE switch to LOW.

6) Set FUNCTION switch to VOLTS.

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
with a light hammer.

RANGE

FUNCTION

TEST

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

– 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

Section 2

GM/CHRYSLER

Testing Sensor s

FORD

TOYOTA/HONDA

Manifold Absolute Pressure (MAP) Sensor

Barometric Pressure (BARO) Sens

2-28

What is It?

How it is

used?

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 fre­quency). 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 turbo­charged engines, the computer also uses the
sensor to monitor boost pressure and operate the
wastegate accordingly.

Manifold Absolute Pressur e MAP/B ARO

Location

When to Test

Harness
Connectors
for MAP
Sensor

(Mating side of
connector shown.)

The sensor is mounted either on the bulkhead, air
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.

• 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.

GM/CHRYSLER

Power

MAP Signal

Ground

FORDVehicle

MAP Signal

Ground

Power

HONDA

Ground Power

Signal

Refer to vehicle service manual for connectors not shown.

Ground

Signal

TOYOTA

GroundPower

Signal

Power

2-29

Section 2

Testing Sensor s

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.

Yellow

Keep sensor connected to vehicle wiring.

• YELLOW to sensor SIGNAL circuit. Use
backprobe adapter.

• BLACK to good vehicle GROUND.

2-30

Backprobe

4) Verify test clips make good contact.

Make sure unused clips are not touching any­thing.

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.

Manifold Absolute Pressur e MAP/B ARO

• 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!

YST

CE BOOSTER

G GAP

U.S.A.

M

9) Ignition key OFF.

HVAC

CRUISE

EGR
VAC
REG

EGR
VAC
REG

BRAKE BOOSTER

FUEL
PRESS
REG.

TO TRANS

MODE

FRONT

OF CAR

12RA C8

10) Check MAP sensor vacuum hose for...

• Correct hook-up.

• Pinches, kinks or collapsed sides.

• Splits, cuts, breaks or clogs

Repair as necessary, then retest. If no
trouble found, go to next step.

2-31

Section 2

HIGH
LOW

POWER OFF

RANGE

VOLTS
OHMS
FREQUENCY

FUNCTION

TEST

Testing Sensor s

11) Check MAP sensor power circuit.

Keep sensor connected to vehicle wiring.

• YELLOW test lead to sensor POWER circuit.
Use backprobe adapter.

• BLACK test lead to good vehicle GROUND.

• RANGE on HIGH.

• FUNCTION on VOLTS.

• Ignition key ON.

Good power circuit:

light ON.

Go to next step.

Bad power circuit:

(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:

Go to next step.

Bad ground circuit:

Repair open in ground circuit wiring, then retest.

Top (or next to top) TEST

TEST light OFF or not in top

TEST light OFF.

Any TEST light ON.

2-32

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.

Manifold Absolute Pressur e MAP/B ARO

14) Check MAP signal wire for short to ground.

•Verify ignition key OFF and MAP sensor wiring
harness disconnected.

• RANGE on LOW.

• FUNCTION on OHMS.

• YELLOW test lead to MAP signal pin on
vehicle harness connector.

• 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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

2-33

Section 2

Mass Air Flow (MAF) Sensors

Testing Sensor s

FLOW

Typical

- F +

MAF
Sensor

What is It?

How it is

Location

When to Test

2-34

used?

This sensor is an electronic module which sends a
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.

The sensor is mounted in the engine incoming air
ducts—typically just behind the air cleaner assem­bly or near the throttle body.

• 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.

Mass Air Flow MAF

Vehicle Harness Connectors for MAF Sensor

(Mating side of connector shown.)

GM

POWER
MAF SIGNAL
GROUND

1988 and Older
RANGE on LOW
FUNCTION on FREQUENCY

POWER
GROUND
MAF SIGNAL

1989 and Newer
RANGE on HIGH
FUNCTION on FREQUENCY

Ford

NOTE:

MAF RETURN is
not connected to
vehicle GROUND.

MAF SIGNAL

MAF RETURN

GROUND

POWER

MAT SIGNAL
MAT RTN
POWER
GROUND
MAF SIGNAL

1988 2.8L only
RANGE on LOW
FUNCTION on FREQUENCY

GROUND
MAF RETURN

MAF SIGNAL

BURN-OFF SIGNAL

POWER

All 5-Pin except 1988 2.8L
RANGE on HIGH
FUNCTION on VOLTS

RANGE on HIGH
FUNCTION on VOLTS

Refer to vehicle service manual for connectors not shown.

2-35

Section 2

Testing Sensor s

Vehicle Harness Connectors for MAF Sensor

(Mating side of connector shown.)

Nissan

MAF
Signal

1985-86 Maxima
1985-86 300ZX
1985-86 300ZX Turbo

Power Ground

1987-88 Maxima
1987-88 200SX SE
1987-89 300ZX

MAF
Signal

PowerGround

Pulsar NX SE
All except 1987-88 1987-88 Pulsar NX SE only

MAF
Signal

MAF
Return

Power Ground

PowerGround

MAF
Signal

PowerGround

MAF
Signal

1987 Pulsar NX
1987 Sentra (E16i)
1988 Pulsar NX XE
1988 Sentra

MAF
Signal

1989-90 Sentra
1990 Pulsar NX


MAF
Signal

PowerGround

GroundPower

MAF
Return

MAF
Signal

PowerGround

PowerGround

MAF
Signal

2-36

1989 and Up Maxima
1990 and Up 300ZX

All Nissan:

RANGE on HIGH
FUNCTION on VOLTS

MAF

Power Ground

Return*
*

May not be used

MAF
Signal

= May not be used

Refer to vehicle service manual for connectors not shown.

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 any­thing.

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

Section 2

Testing Sensor s

– 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.

2-38

RANGE

FUNCTION

TEST

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

11) Check MAF sensor power circuit.

Keep sensor connected to vehicle wiring.

• YELLOW test lead to sensor POWER circuit.
Use backprobe adapter.

• BLACK test lead to good vehicle GROUND.

• RANGE on HIGH.

• FUNCTION on VOLTS.

• Ignition key ON.

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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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.
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.

• RANGE on LOW.

• FUNCTION on OHMS.

• YELLOW test lead to MAF signal pin on vehicle
harness connector.

• 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.

Do not probe

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.

2-39

Section 2

Testing Sensor s

Typical VAF Sensor

What

is It?

How it is

used?

Location

AIR FLOW

Referred to as Vane Air Flow
(VAF) sensor or Air Flow Meter

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).

The computer needs to know incoming air flow to properly
adjust air/fuel mixture and ignition timing for varying
engine load and operating conditions.

The sensor is mounted in the engine incoming air duct ­between the air cleaner and the throttle body.

2-40

When to

Test

What to

Inspect

• 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.

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.

V ane Air Flow V AF

Sensor Connectors

Toyota

1234567

Red Yellow
Black

Black

#1

#2

Black

Black

YellowRed

YellowRed

Yellow

*Toyota uses
two sensor
types. Try
hook-up #1
first. If good

A *

test results are
not obtained,
retest using
hook-up #2
before judging
sensor.

A *

Nissan

A *

#1

A *

#2

Red

1234567

Black Yellow

12345671234567

Yellow

*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.

Yellow

= NOT

USED

Black

Black

Red

B

C

A

B

B

Black

Yellow

Ford

A

Black Black

Red

Refer to vehicle service manual
for connectors not shown.

Yellow

Hook up as follows: Red lead to sensor power pin.

Yellow lead to sensor signal pin.
Black lead to sensor ground pin.

Yellow

Yellow

Black

B

2-41

Section 2

Testing Sensor s

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.

an asterisk (*) only
sary because some sensors look alike, but have different internal connec­tions.

Sensor may be tested on or off vehicle.
Warning: Observe all safety precautions (see page ii) if testing sensor on

vehicle.

one of the two hook-ups has to test O.K. This is neces-

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.

Exception: If two hook-ups are marked with

2-42

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)

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

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

(*) only
necessary because some sensors look alike, but have
different internal connections.

3) Verify test clips make good contact and do not touch
each other.

Make sure unused clips are not touching anything.

4) Set RANGE switch to HIGH.

5) Set FUNCTION switch to VOLTS.

6) Operate sensor - Watch TEST light for results.

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

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 OR light movement is erratic, showing a sudden jump
or dip during smooth sensor operation.

one of the two hook-ups has to test O.K. This is

- TEST light smoothly moves up or down as

- TEST light position does not change during

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

Section 2

Testing Sensor s

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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

3) Verify test clips make good contact and do not touch each other.

Make sure unused clips are not touching anything.

4) Set RANGE switch to HIGH.

5) Set FUNCTION switch to OHMS.

6) Note TEST light position on tester.

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 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 moved downwards below original position.

- TEST light position did not change during test.

2-44

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.

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 compo­nent drawing.

3) Verify test clips make good contact and do not touch

HIGH
LOW

POWER OFF

RANGE

VOLTS
OHMS
FREQUENCY

FUNCTION

TEST TEST

each other.

Make sure unused clips are not touching anything.

4) Set RANGE switch to HIGH.

5) Set FUNCTION switch to OHMS.

6) Operate sensor - Watch TEST light for results.

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

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

Section 2

Testing Sensor s

Magnet

To
Computer

Reluctance Sensor Operation

Wire Coil

Tooth

NS

Air Gap

Reluctor Ring

Rotation

Positive

SENSOR

Zero

VOLTAGE

Negative

ROTATION

Typical Sensor Signal Voltage

Crankshaft/Camshaft Position sensors

What is It

and

How is It

Used?

— 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:

Flywheel, Distributor Pick-Up, Camshaft Position, Cylinder,
TDC and RPM.

— Similar sensors are used in anti-lock brake and electroni­cally shifted transmission systems. These sensors have
names such as:

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

tance

and

Optical

types which are in limited use.

Wheel Speed, Vehicle Speed and

Hall Effect.

Crankshaft Position, Crank Angle,

Magnetic Reluc-

These are described below along with

2-46

• 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.

Crankshaft/Camshaft Position

SHUTTER

HALL

POWER

GROUND

SIGNAL

Typical Hall Effect Sensor Typical Sensor Signal Voltage

SWITCH

MAGNET

HIGH

SIGNAL
VOLTAGE

LOW

ROTATION

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

Section 2

Testing Sensor s

Where is

It?

When to

Test

What to

Inspect

— 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.

— 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.

• 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:

49 through 2-52). Poor connections at sensor or computer.
Faulty sensor wiring (open or short circuits).

Sensor operation (see tests on page 2-

2-48

– Magnetic Reluctance:

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:

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:

detector assembly. Broken or worn teeth on the distributor
shaft (if used) or sensor shaft.

Foreign objects in gap between Hall sensor

Dirt in the rotor blade slots or light source/

Too much gap between sensor

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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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.

Make sure unused clips are not touching anything.

6) Set RANGE switch to LOW.

7) Set FUNCTION switch to VOLTS.

8) Operate sensor - Watch TEST light for results.

(Note: Ignore any RICH / LEAN light flashes.)

Crankshaft/Camshaft sensor:

–

Crank engine.

STAY AWAY from moving engine parts.

2-49

Section 2

TEST

Testing Sensor s

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:

jack stands and observe all safety precautions (see
page ii). Give the wheel a quick spin in either
direction to test.

Good sensor

testing. Position and range of TEST light activity
varies with sensor type.

Bad sensor

9) Testing is complete.

Set RANGE switch to POWER OFF and remove all test
leads.

- TEST lights flicker or stay ON during

- TEST lights OFF during testing.

Raise wheel off ground. Use

2-50

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.

RANGE

FUNCTION

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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.

Make sure unused clips are not touching anything.

7) Set RANGE switch to LOW.

8) Set FUNCTION switch to FREQUENCY.

9) Operate sensor - Watch PULSE light for
results.

(Note: Ignore any TEST light action.)

2-51

Section 2

PULSE

Testing Sensor s

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

during cranking (varies with sensor type).

Bad sensor

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.

- PULSE light flashes or stays ON

- PULSE light OFF during cranking.

2-52

Good sensor

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

10) Testing is complete.

Set RANGE switch to POWER OFF and remove all test
leads.

Red

Black

Chrysler Distributor

Hall Effect

- Single flash on PULSE light whenever

- PULSE light OFF during testing.

Red

Yellow

Yellow Black

Ford Distributor Hall Effect
(PIP Sensor, TFI-IV Ignition

Section 2

Section

3

Testing
Ignition Modules

T roubleshooting

Tips

6DLC24

5AAC28

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.

Has the vehicle been serviced recently? Some­times 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

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 installa­tion 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

and do not touch each other.

3) Set RANGE switch to LOW.

4) Set FUNCTION switch to FREQUENCY.

5) 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.

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

RANGE

FUNCTION

PULSE

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

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

Section 3

GM

4 and 5 pin

Testing Ignition Modules

Black

*

Yellow

Red

Green

3-4

Green

Test clip must

*

touch both base
plate and bushing

*

Black

BUSHING

BASE

PLATE

Yellow

Red

GM

7 pin

Test 1

Black

Black

Green

Test 2

Green

*

Yellow

Red

*

Yellow

Red

Blue Jumper

Black

Green

*

*

Test clip must
touch both base
plate and bushing

BUSHING

BASE

PLATE

*

Yellow

Red

Black

Green

Blue Jumper

Yellow

Red

3-5

Section 3

GM

8 pin

Testing Ignition Modules

Green

PN

Test 1

Test 2

Green

SIDE

GBRE+C

C

GBRE

YellowRed

Black

PN

VIEW

END
VIEW

SIDE

GBRE+C

VIEW

3-6

Red

Yellow

C

Blue Jumper

GBRE

END
VIEW

Black

Ford

Dura-Spark

Blue Jumper

Red

Black

Yellow

Green

Ford

TFI

Black

Blue Jumper

456

Red

White

Black

(or Black/Green)

Green

Orange

Green

MODULE

Note: Dura-Spark
ignition modules
come in several
versions with different
connector types.
Make connections
based on ignition
module
Other module wires
not used for testing.

wire colors.

SIDE
VIEW

3
2
1

END
VIEW

Red

Yellow

3-7

Section 3

Ford

TFI-IV

Test 1: Connect leads as shown.

Testing Ignition Modules

Black

Ford

TFI-IV

Test 2: Move Green lead to pin 5.

Other leads remain in original position

Green

789

SIDE
VIEW

Test 1: Connect leads as shown.
Test 2: Move Green lead to pin 5.

Other leads remain in original position

6
5
4
3
2
1

END
VIEW

Red

Yellow

Green

3-8

SIDE
VIEW

END
VIEW

Red

Yellow

Black

Chrysler

4 and 5 pin

Black

Red

5-pin type shown.
4-pin uses same hook-up.

Yellow

Green

1

2

4

3

5

Magetic Reluctance Pick-up

Yellow

5

1

4

2

3

Black

Green

Red

Hall Effect Pick-up

3-9

Section 3

Honda

Black

Testing Ignition Modules

3

1

2

4

Yellow

3-10

Green Red

Red

3

1

2

4

Yellow

Red

Green Green

Black

Yellow

3

1

2

4

Connect BLACK test lead
to igniter mounting holes
or a metal ground inside
distributor.

Honda/Nissan

Yellow

CB

W

I

Not present on
some modules.

Red

Yellow

Black

Connect BLACK test lead
to a good ground inside
distributor.

Red

Yellow

Red

Green

Test clip must touch both
base plate and bushing

IMPORTANT

1) Remove distributor from
engine before testing.

2) Module remains inside
distributor during test.

EBI

Bushing

Base plate

Black

Red

Yellow

Black

Connect BLACK test lead
to a good ground inside
distributor.

EB C I

Black

Connect BLACK test lead
to a good ground inside
distributor.

3-11

Section 3

Testing Ignition Modules

Nissan

SB

Red

Nissan
One-Coil System
(Photo pick-up)

Nissan uses two types
of connector wiring.

*

Module is good if either
hook-up tests O.K.

**

Pick-up pins

E

I

Green

1987-1989 300ZX only

OR

Test clip must touch both
base plate and bushing

Bushing

Base plate

Black

Yellow

GreenYellow

Black

3-12

Green Yellow

Green

Black

Yellow

14
23

Black

Yellow

Black

**

OR

Green Yellow

14
23

Green

Black

Nissan
Two-Coil System
(Photo pick-up)

Nissan uses two types
of connector wiring.

*

Module is good if either
hook-up tests O.K.

Black

GreenYellow

Green

Green

Black

14
23

Yellow

Black

**

OR

Green Yellow

14
23

Black

Yellow

Not present on
some modules.

3-13

Section 3

Testing Ignition Modules

Toyota

Yellow

Use a paper clip to
connect test lead.

Red

Black

Connect BLACK test
lead to igniter mounting
hole or good vehicle
ground.

Green

3-14

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

Toyota

Red

Yellow

Green

BROWN

BLACK

Black

Connect
BLACK test
lead to igniter
mounting hole
or good vehicle
ground.

Yellow

C Ext B I, TF

Red

Green

3-15

Section 3

Toyota

Red

Yellow

Use a paper clip to
connect test lead.

Testing Ignition Modules

Green

Yellow

3-16

Black

Connect

BLACK test

lead to igniter

mounting hole

or good vehicle

ground.

Green

Toyota

Green

Black

Red

Connect

BLACK test

lead to igniter

mounting hole

or good vehicle

ground.

Yellow

Use a paper clip to
connect test lead.

3-17

Section 3

Toyota

Testing Ignition Modules

Black

Connect BLACK
test lead to igniter
mounting hole or
good vehicle
ground.

3-18

Green

Red

Yellow

Use a paper clip to
connect test leads.

Toyota

Yellow

Red

Green

Green

Black

Connect BLACK
test lead to igniter
mounting hole or
good vehicle
ground.

Yellow

Red

3-19

Section 3

Toyota

Testing Ignition Modules

Yellow

Red

Green

3-20

Black

Connect
BLACK test
lead to igniter
mounting hole
or good vehicle
ground.

Toyota

Red

Green

Yellow

Red

Red

Green

+

B

SG

C


C


+

B

SG

Yellow

Green

Yellow

C

B

F

T

Green

Connect BLACK test lead
to igniter mounting holes.

Yellow

Black

Red

F

C

T



B

3-21

Notes

3-22

Section 2

Section

More Uses for the

4

Ignition Module

&

Engine Sensor T ester

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

RANGE

FUNCTION

VOLTS

over5

4.5
4

3.5
3

2.5
2

1.5
1
.5

LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

TEST

1) Set FUNCTION switch to VOLTS.

2) Set RANGE switch to HIGH.

3) Connect BLACK test lead to circuit ground.

4) Probe with YELLOW test lead.
Warning: Do not connect to secondary ignition

circuits - dangerous voltages present!

5) TEST light position indicates measured voltage.

Each light represents a 0.5 volt step along a
span of 0.5 to 5 volts.

• Top TEST light ON - voltage is 5 volts, or
higher.

• Other TEST lights ON - see illustration for
voltage level.

• All TEST lights OFF - voltage is less than 0.5
volts, not present or negative polarity.

Important:

• Always make sure all connections are good at
the contact points.

• 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

Section 4

Continuity Checks

Test wiring, ground connections, switch operation, relay contacts, or similar.
Important:

• Do continuity tests on

• 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

RANGE

FUNCTION

LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

1) Set RANGE switch to HIGH.

2) Set FUNCTION switch to OHMS.

3) Connect YELLOW test lead to one end of circuit (such as
wire, switch or relay contact).

4) Connect BLACK test lead to other end of wire, switch or
relay.

Yellow

Black Black

TEST

Short

circuit

unpowered circuits only.

Yellow

TEST

Open

circuit

5) TEST light position indicates
amount of continuity.

• All TEST lights OFF -

Short Circuit

(measured resistance is 200 ohms,
or less).

• Top TEST light ON -

Open Circuit

(measured resistance is 7 Kohms,
or higher).

Other TEST lights ON mean circuit has
resistance between 200 ohms and 7 K
ohms.

RANGE

FUNCTION

4-2

HIGH
LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

Low Resistance Checks

• RANGE switch on LOW.

• FUNCTION switch on OHMS.

• Use YELLOW and BLACK test leads.
All TEST lights OFF - resistance is 30 ohms, or less.
Top TEST light ON - resistance is 300 ohms, or higher.

Other TEST lights ON mean resistance is between 30 ohms and
300 ohms.

More Uses for the Ignition Module/Sensor Tester

Continuity Checks (cont.)

Yellow Black Yellow Black

TEST

Switch
Closed

Yellow Black Yellow Black

Switch

Open

TEST

12V 12V

TEST

Ground

Connection

TEST

No

Ground

Connection

4-3

Section 4

Diode Checks

Tests diodes and rectifiers for proper operation.

HIGH

RANGE

FUNCTION

LOW

POWER OFF

VOLTS
OHMS
FREQUENCY

1) Set RANGE switch to HIGH.

2) Set FUNCTION switch to OHMS.

3) Connect TEST leads as shown in Figure 1.

( YELLOW to anode — BLACK to cathode)

bottom TEST light should be ON. If a

4) The
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)

top TEST light should be ON. If a different

6) The
TEST light is on or all lights are off, the diode is
defective.

4-4

Note: Always make sure all connections are good. If
necessary, scrape away corrosion, paint, etc. at the
contact points.

Yellow Black

TEST

Black Yellow

TEST

Fig. 2Fig. 1

Warranty

(Garantia)

FULL ONE (1) YEAR WARRANTY

Actron Manufacturing Company, 9999 Walford Avenue, Cleveland, Ohio 44102­4621, 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 dam­ages 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 dis­claimer 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 con­nected with it for loss or damages suffered through reliance on any information
contained in this manual or misuse of the accompanying product. Actron Manufac­turing 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

Tel: [phone]
Fax: [phone]

Product Information & Repair

Actron - Europe

Coppen Road, Dagenham,
Essex RM8 1NU
UNITED KINGDOM

Tel: [phone]
Fax: [phone]

Product Information & Repair

Actron - Europe

60 Rte de St Gemme
78860 St NOM LA BRETECHE
FRANCE

Tel: [phone]
Fax: [phone]

Product Information Only

®

Actron Manufacturing Company

9999 Walford Avenue
Cleveland, Ohio 44102-4696


©1997, Actron Manufacturing Company

Made in the U.S.A.


Part No. 2-221301