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

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

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.

6-3

Section

Tester

— 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-

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.

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

(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

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

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

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 &

ENGINE SENSOR TESTER

TEST

Tester Bas ics

2 4

Backprobe

Adapter

To Sensor

RANGE

FUNCTION

HIGH LOW

POWER OFF

VOLTS OHMS FREQUENCY

Select LOW, VOLTS

PULSE

RICH

LEAN

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.

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

Jumper Lead

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.

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

T roubleshooting

Tips

HVAC

YST

CE BOOSTER

G GAP

U.S.A.

CRUISE

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

= Test B, page 2-12

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

Yellow

Red

Yellow

Red

Black

FORD

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

TOYOTA

TOYOTA/NISSAN

BlackYellowRed

BlackYellow

Yellow Black

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

+ 61 hidden pages