Engine Controls - System/component Tests: Other Volvo 850 I

Preliminary Checks

1. Warm engine to normal operating temperature. Turn off engine. If turbine shaft does not stop rotating shortly after engine stops, remove intake hose from compressor housing.
2. Verify compressor wheel rotates freely. Ensure compressor wheel does not scrape against compressor housing when wheel is pushed radially or axially.

COMPUTERIZED ENGINE CONTROLS

ELECTRONIC CONTROL UNIT - FUEL INJECTION (850)

Note. When measuring resistance and voltage at ECU, use Measuring Unit (981 3190 ) and Adapter (981 3195 ). DO NOT measure resistance and voltage at ECU connector. Before disconnecting/connecting control unit connector, disconnect negative battery cable.

Power Circuit Check

Ensure ignition is off. Connect voltmeter between measuring unit terminals No. 20 and 10. Battery voltage should be present. Connect voltmeter between terminals No. 20 and 30. Turn ignition on. Battery voltage should be present. If voltage is not as specified, check wiring, fuse No. 1, and electrical connections. Turn ignition off.

Ground Circuit Check

1. Connect ohmmeter between ground and measuring unit terminal No. 20, then between ground and measuring unit terminal No. 29. Ohmmeter should indicate about zero ohms. If about zero ohms is not present, check control unit grounds.
2. Connect ohmmeter between measuring unit terminal No. 20 and measuring unit terminals No. 8, 12, 14, and 23. Ohmmeter should indicate about zero ohms in all cases. If reading is too high, repeat test using new fuel injection ECU.

ELECTRONIC CONTROL UNIT - IGNITION (850)

Note. When measuring resistance and voltage at ECU, use Measuring Unit (981 3190 ) and Adapter (981 3195 ). (Scheme 35) DO NOT measure resistance and voltage at ECU connector. Before disconnecting/connecting control unit connector, disconnect negative battery cable.

1. Connect voltmeter between measuring unit terminals No. 20 and 43. Operate starter motor. Voltmeter should indicate .7-1.3 volts. If voltage is not as specified, repeat test using new ECU.
2. To check distributor ignition signal to fuel injection ECU, connect voltmeter between measuring unit terminals No. 20 and 52. Operate starter motor. Voltmeter should indicate about 5-7 volts. If voltage is not as specified, repeat test using new distributor ignition ECU.
3. Turn ignition off. To check voltage supply to ECU, connect voltmeter between measuring unit terminals No. 20 and 10. Battery voltage should be present. Turn ignition on. Connect voltmeter between measuring unit terminals No. 20 and 30. Battery voltage should be present. If battery voltage is not present, check wiring.

Connect ohmmeter between ground and measuring unit terminal No. 20, then between ground and terminalNo. 29. In both cases, ohmmeter should indicate about zero ohms. Connect ohmmeter between measuring unit terminals No. 20 and 2, then between terminals No. 20 and 15. In both cases, ohmmeter should indicate about zero ohms.

ELECTRONIC CONTROL UNIT - FUEL INJECTION (940)

Note. When measuring resistance and voltage at ECU connector, DO NOT probe into front of connector. Probe only through side of connector, just enough to make a good electrical contact. Terminal identification numbers are stamped on side of ECU connector.

1. Turn ignition switch to OFF position. Disconnect fuel injection ECU connector. Fuel injection ECU is located on right side of instrument panel, under kick panel. Push out clip and disconnect ECU connector.
2. Remove cover from ECU connector to expose terminal identification numbers. Visually inspect all terminal connector sleeves to ensure all terminals are at same height.

Power Circuit Checks

1. Connect voltmeter leads between ECU connector terminal No. 35 and ground.
2. Turn ignition switch to ON position. Voltmeter should read 12 volts. Also, crank engine and ensure battery voltage exists while engine is being cranked.

Voltage Supply For Memory Check (940)

1. Connect voltmeter between fuel injection ECU terminal No. 4 and ground. Turn ignition on. Reading should be 12 volts. Connect diagnostic unit select cable to connector terminal No. 2. See SELF-DIAGNOSTIC SYSTEMS in «TESTS W/CODES - LH 2.4/EZK 116 IGNITION»(ref-15203) article in the ENGINE PERFORMANCE Section. Connect voltmeter between fuel injection ECU terminal No. 12 and ground.
2. Reading should be 12 volts. Press button on diagnostic unit. Voltage should drop to zero. If voltage reading is 12 volts when button is pressed, check diagnostic unit. If voltage is not present at fuel injection ECU, check for voltage at diagnostic unit output connector.
3. Connect voltmeter between Blue wire terminal in diagnostic unit and ground. Reading should be 12 volts. Turn ignition off. Connect ohmmeter between Black wire terminal in diagnostic unit and ground. Reading should be zero ohms. Connect ohmmeter between select cable for diagnostic unit and terminal beneath function select button.
4. Reading should be infinite. Press select button; resistance should be zero ohms. Connect Red lead of a diode tester to terminal beneath LED. Connect Black lead to select cable. If diode tester gives reading, LED is okay. If diode tester does not give reading, install new diagnostic unit. See SELF-DIAGNOSTIC SYSTEMS in «TESTS W/CODES - LH 2.4/EZK 116 IGNITION»(ref-15203) article in the ENGINE PERFORMANCE Section.

Connect ohmmeter between ground and fuel injection ECU terminals No. 5, 17, 19 and 29 (LH Jetronic 2.4 fuel system) or terminals No. 5, 17 and 19 (Regina fuel system). In each case, reading should be zero ohms. Wires are grounded to intake manifold.

ELECTRONIC CONTROL UNIT - IGNITION (940)

Note. When measuring resistance and voltage at ECU connector, DO NOT probe into front of connector. Probe only through side of connector, just enough to make a good electrical contact. Terminal identification numbers are stamped on side of ECU connector.

Note. Before removing ignition control unit connector, remove fuse No. 31.

1. Turn ignition off. Disconnect ignition ECU connector. ECU is located behind panel on right side of accelerator pedal.
2. Push out clip and disconnect ECU connector. Remove cover from ECU connector, exposing terminal identification numbers. Visually inspect all terminal connector sleeves to ensure all terminals are at same height.

Connect a voltmeter between ignition ECU terminal No. 5 (Brown wire) and ground. Voltmeter should indicate 12 volts. If voltage is not present, check circuit between ignition ECU terminal No. 5 and fuse block (940).

Ground Circuit Checks

Turn ignition switch to OFF position. Connect ohmmeter between ground and electronic control unit terminals No. 14 and 20. (Scheme 34) Resistance should be zero ohms.

Scheme 34

ELECTRONIC CONTROL UNIT (960)

Note. When measuring resistance and voltage at ECU, use Measuring Unit (999 3070 ). (Scheme 35) DO NOT probe connector. Before disconnecting/connecting control unit connector, remove fuse No. 24.

Preliminary Check

Turn ignition off. Disconnect ECU connector. ECU is located behind panel on right side of accelerator pedal. Visually inspect all terminal connector sleeves to ensure no terminals are damaged.

Ensure ignition is off. Connect a voltmeter between measuring unit terminals No. 18 and 19, and then between terminals No. 36 and 19. Battery voltage should be present in both cases. If voltage is not as specified, check fuse, wiring and relay. Turn ignition on. Voltage should decrease from 12 volts to about .1 volt at terminal No. 36.

Turn ignition off. Connect an ohmmeter between ground and measuring unit terminals No. 19, 24, 26, 30,and 48. Ohmmeter should indicate about zero ohms in all cases.

ENGINE SENSORS & SWITCHES

CAMSHAFT POSITION SENSOR (850)

1. When measuring voltage at ECU, use Measuring Unit (981 3190) and Adapter (981 3195). (Scheme 35) DO NOT measure voltage at ECU connector. Before disconnecting/connecting ECU connector, disconnect negative battery cable.
2. To install measuring unit, remove distributor ignition ECU. Press adapter onto distributor ignition ECU and pull lead upward through slot beside module. Press distributor ignition ECU, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
3. Connect voltmeter between measuring unit terminals No. 20 and 4. Operate starter motor. Voltage should vary between 0-5 volts. If voltage reading is incorrect, check camshaft position sensor supply voltage. If voltage is present, check control signal to power stage.
4. To check voltage supply to camshaft position sensor Hall Effect generator, connect voltmeter between measuring unit terminalsNo. 20 and 14. Voltmeter should indicate about 10 volts. If voltage is present but signal is absent, repeat test using new camshaft position sensor.

Scheme 35

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn ignition on.
2. Remove fuse No. 31 to prevent engine from starting. Connect voltmeter between measuring unit terminals No. 8 and 19. Operate starter motor. Voltmeter should oscillate between.1-.5 volts. Reinstall fuse No. 31.
3. If signal is absent or faulty, turn ignition on. Using a voltmeter, probe between terminals No. 10 and 30. Voltage should be about 11 volts.
4. Turn ignition off. Ensure terminal No. 30 is grounded. Connect an ohmmeter between terminals No. 30 and 19. Ohmmeter should read zero ohms.

COOLANT TEMPERATURE SENSOR

1. Disconnect Coolant Temperature Sensor (CTS) connector. Connect ohmmeter leads between CTS terminals.
2. Ohmmeter should read as specified. See COOLANT TEMPERATURE SENSOR RESISTANCE table.

COOLANT TEMPERATURE SENSOR RESISTANCE

CRANKSHAFT POSITION SENSOR (960)

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35)
2. Connect a millivoltmeter between measuring unit terminals No. 47 and 48. Operate starter motor. Voltmeter should read 300-400 millivolts.
3. Turn ignition off. If signal is not present or faulty, connect ohmmeter between terminals No. 47 and 48. Resistance should be 200-400 ohms, depending on pick-up temperature.
4. Connect ohmmeter between terminals No. 48 and 19, and between terminals No. 48 and 30. Resistance should be zero ohms.

MASS AIRFLOW METER (940)

1. Remove rubber sleeve from airflow meter to uncover wire connector. DO NOT disconnect connector. Using a voltmeter, backprobe connector terminals. Connect voltmeter leads between ground and terminal No. 5 on mass airflow connector.
2. Voltage reading should be 12 volts. Connect voltmeter leads between terminals No. 1 and 5 on mass airflow connector. Voltage reading should be 12 volts.

MASS AIRFLOW METER/SENSOR (850)

1. Connect Measuring Unit (981 3190) and Adapter (981 3195) to fuel injection ECU. (Scheme 35) DO NOT measure resistance and voltage at ECU connector. Before disconnecting/connecting control unit connector, disconnect negative battery cable.
2. Remove ECU cover located in right front engine compartment. Remove both fuel injection and distributor ignition ECUs located in right front of engine compartment. Press adapter into ECU base. Position adapter lead at rear of ECUs and thread through slot next to distributor ignition module.
3. Press distributor ignition ECU into position first to avoid damage to adapter lead. Press fuel injection control unit, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
4. Turn ignition on. Connect voltmeter between measuring unit terminals No. 13 and 20. About 2.7 volts should be present. Start engine. About 3.5 volts should be present at idle with engine hot. Turn engine off. If voltages are okay, go to step 6) and check MAF ground circuit. If voltages are not okay, go to next step.
5. Turn ignition on. Connect voltmeter between MAF connector terminal No. 4 (White wire) and ground. Voltage should be about 2.7 volts. Start engine. Voltage should be about 3.5 volts during idle with engine hot. If voltages are correct, check voltage supply for an open or short circuit. If voltages are incorrect, go to next step and check MAF ground circuit.
6. Turn ignition off. Connect ohmmeter between MAF connector terminal No. 2 (Green/Red wire) and ground, then between connector terminal No. 1 (Brown/White wire) and ground. Ohmmeter should indicate about zero ohms in both instances. If readings are okay, go to step 8). If readings are incorrect, go to next step.
7. Ensure ignition is off. Connect ohmmeter between measuring unit terminals No. 20 and 8, then between terminals No. 20 and 12. Ohmmeter should indicate about zero ohms in both instances. If readings are incorrect, repeat test using new fuel injection ECU. If readings are correct, go to next step and check MAF voltage supply.
8. Turn ignition on. Connect voltmeter between ground and MAF connector terminal No. 3 (Green wire). Voltmeter should indicate battery voltage. If voltage is not present, check for an open or short circuit in voltage supply. If voltage is present, repeat test using new MAFsensor.

MASS AIRFLOW METER (960)

1. Turn ignition off and remove fuseNo. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35)
2. To ensure airflow meter is grounded, connect ohmmeter between measuring unit terminals No. 19 and 26. Zero ohms should be present. Connect ohmmeter between airflow meter connector terminal No. 1 (Brown wire) and ground. Reading should be about zero ohms.
3. Connect ohmmeter between measuring unit terminals No. 7 and 26. Reading should be about 2.5-4 ohms. If not to specification, measure resistance between airflow meter terminals No. 2 (Brown/White wire) and No. 3 (Green/Yellow wire).
4. Turn ignition on. Connect voltmeter between terminals No. 7 and 19. About 1.4 volts should be present. Start engine. Voltage should increase to 2.3-2.6 volts when idling. Voltage should be 2.3 volts with engine hot.
5. If voltage reading is too low, connect voltmeter between measuring unit terminals No. 25 and 19. Increase speed to 1800 RPM and stop engine. Voltmeter should read about 4 volts.

HEATED OXYGEN SENSOR (HO2S - 940)

1. Warm engine to normal operating temperature. Connect exhaust gas analyzer. Disconnect HO2S sensor wire (at HO2S sensor) from ECU.
2. Connect a jumper wire between ECU wiring (HO2S sensor harness side) and ground. CO content should increase, indicating ECU and its connections are okay.
3. Connect a voltmeter to HO2S sensor. While engine is running, voltmeter should fluctuate at about .5 volt if CO constant is normal. Replace HO2S sensor if not within specification.
4. To check voltage supply to HO2S sensor, connect voltmeter between ground and terminal No. 1 of 2-wire connector located next to firewall. Voltage reading should be battery voltage.
5. To check HO2S heater resistance, connect ohmmeter between oxygen sensor harness terminal No. 2 (Black wire) and ground. Connector is located next to firewall. With a cold oxygen sensor, resistance should be 3 ohms. With oxygen sensor warmer than 660°F (350°C), resistance should be 13 ohms. Replace oxygen sensor as necessary.

HEATED OXYGEN SENSOR (HO2S) & PREHEATER RESISTOR (850)

1. Connect Measuring Unit (981 3190 ) and Adapter (981 3195 ) to fuel injection ECU. (Scheme 35) DO NOT measure resistance and voltage at ECU connector. Before disconnecting/connecting control unit connector, disconnect negative battery cable.
2. Remove ECU cover located in right front engine compartment. Remove both fuel injection and distributor ignition ECUs. Press adapter into ECU base. Position adapter lead at rear of ECUs and thread through slot next to distributor ignition module.
3. Press distributor ignition ECU into position first to avoid damage to adapter lead. Press fuel injection control unit, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
4. Connect voltmeter between measuring unit terminals No. 22 and 23. Start engine. After about 30 seconds, voltage should vary between.1-.9 volt. If voltage does not vary but remains constant at.5 volt, HO2S or wiring is defective.
5. To check voltage supply to HO2S, turn ignition on. Connect volt-meter between measuring unit terminals No. 20 and 28. If battery voltage is present, go to next step. If battery voltage is not present, check HO2S wiring.
6. If battery voltage was present in step 5), connect voltmeter between measuring unit terminals No. 28 and 20. Start engine. If voltage reading falls from battery voltage to about.4 volt, go to next step. Turn engine off. If voltage reading does not fall from battery voltage to about.4 volt, ECU is probably defective.
7. Stop engine. To check preheater resistor, connect ohmmeter between measuring unit terminals No. 19 and 28. Ohmmeter should indicate about 3-13 ohms, depending on resistor temperature.

HEATED OXYGEN SENSOR (HO2S) & PREHEATER RESISTOR (960)

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn igni-tion on.
2. To check oxygen sensor signal, connect voltmeter between measuring unit terminals No. 28 and 30. Voltmeter should oscillate between.1-1 volt after a short interval. If voltage remains constant at zero volts, sensor is interpreting mixture as lean. If voltage is constant at one volt, sensor is interpreting mixture as rich. Disconnect measuring unit.
3. To check voltage to oxygen sensor, start engine. Connect voltmeter between terminals No. 1 and 2 in starter motor 2-pin connector. Voltmeter should indicate battery voltage. If no voltage is present, check fuse No. 30. If voltage is present, go to next step.
4. Stop engine. To check preheater resistor, disconnect starter motor connector. Connect ohmmeter between starter motor connector terminals No. 1 and 2. About 3-13 ohms should be present, depending on resistor temperature.

THROTTLE SWITCH (940)

1. Turn ignition switch to OFF position. Disconnect fuel injection ECU connector. Terminal identification numbers are stamped on side of ECU connector. Connect ohmmeter between fuel injection ECU terminal No. 2 and ground. With switch closed, reading should be zero ohms. Press accelerator pedal slightly. Resistance should increase to 2000-3000 ohms (switch opens).
2. Connect ohmmeter between fuel injection ECU terminal No. 3 and ground. Reading should be infinite. Press accelerator pedal to floor. Reading should be zero ohms. If a problem is found during check, perform same checks at throttle switch connector.
3. To check and adjust throttle switch, open throttle slightly and listen to switch. A click should be heard as soon as throttle is opened. If switch appears to be out of adjustment, loosen mount screws. Turn switch slightly clockwise, and then turn switch counterclockwise until switch clicks. Tighten mount screws, and check setting.

THROTTLE SWITCH (850)

1. Connect Measuring Unit (981 3190 ) and Adapter (981 3195 ) to fuel injection ECU. (Scheme 35) DO NOT measure resistance and voltage at ECU connector. Before disconnecting/connecting control unit connector, disconnect negative battery cable.
2. Remove ECU cover located in right front engine compartment. Remove both fuel injection and distributor ignition ECUs located in right front of engine compartment. Press adapter into ECU base. Position adapter lead at rear of ECUs and thread through slot next to distributor ignition module.
3. Press distributor ignition ECU into position first to avoid damage to adapter lead. Press fuel injection control unit, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
4. To check throttle switch signal, connect voltmeter between measuring unit terminals No. 1 and 14. Turn ignition on. Voltmeter should indicate about.6 volt in idling position and about 4.2 volts in full-load position. Turn ignition off.
5. If signal is not present or not to specification, connect voltmeter between measuring unit terminals No. 2 and 20. Turn ignition on. Voltmeter should indicate about 5 volts. Turn ignition off. To check ground, connect ohmmeter between measuring unit terminals No. 14 and 20. Ohmmeter should indicate about zero ohms.
6. If no voltage was present or ground is faulty, check wiring for short to ground or voltage. If wiring is okay, repeat test using new fuel injection ECU. If voltage supply was present and ground is okay, go to next step and check throttle switch resistance.
7. Ensure ignition is off. Connect ohmmeter between measuring unit terminals No. 14 and 2. Ohmmeter should indicate about 1800-2200 ohms. Connect ohmmeter between terminals No. 14 and 1. Ohmmeter should indicate about 1000 ohms when throttle is at idle position and about 2600 ohms when throttle is at full load.
8. If resistance is incorrect or zero, measure directly at throttle switch connector to determine if fault is in switch or wiring. Replace switch as necessary.

THROTTLE SWITCH (960)

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn ignition on.
2. To check throttle switch signal, connect voltmeter between measuring unit terminals No. 30 and 53. Voltmeter should indicate about.5 volt at idle and about 4.5 volts at full load.
3. If signal is absent or faulty, check for a 5-volt reference signal between measuring unit terminals No. 12 and 30. Voltmeter should indicate 5 volts.
4. Turn ignition off. Connect an ohmmeter between measuring unit terminals No. 19 and 30. Ohmmeter should indicate about zero ohms. Check resistance between measuring unit terminals No. 53 and 30. Resistance should be about 1000 ohms at idle and about 700 ohms at full load.

FUEL INJECTION MAIN RELAY (940)

Connect voltmeter between fuel injection ECU terminal No. 9 and ground. Connect a jumper wire between fuel injection ECU terminal No. 21 and ground. Relay should close and voltmeter should indicate battery voltage. Replace as necessary.

FUEL PUMP RELAY (940)

Connect jumper wire between fuel injection ECU terminal No. 21 and ground. Connect another jumper wire between fuel injection ECU terminal No. 20 and ground. Fuel pump relay should close and fuel pump should run. Replace relay as necessary.

Scheme 36

Scheme 37

1. Remove fuel pump relay. (Scheme 36) Connect jumper wire between fuel pump relay terminals No. 1 and 3. (Scheme 37) Turn ignition on. If fuel pump does not start, go to next step. If fuel pump starts, replace fuel pump relay.
2. Turn ignition off. To check relay ground, connect ohmmeter between ground and fuel pump relay terminal No. 2. (Scheme 37) Ohmmeter should indicate about zero ohms. If ohmmeter does not indicate about zero ohms, check wiring between fuel pump relay and ground.
3. To check fuel pump relay voltage supply, connect voltmeter between ground and fuel pump relay terminal No. 1. (Scheme 37) Turn ignition on. Battery voltage should be present. If battery voltage is not present, check wiring between fuel pump relay and fuse No. 2.
4. Turn ignition off. Connect ohmmeter between ground and relay terminal No. 3. (Scheme 37) About 1.5 ohms should be present. If about 1.5 ohms are not present, check resistance at fuel pump connector to determine whether fault is in pump or wiring.
5. To check fuel injection control signal to fuel pump relay, connect voltmeter between ground and fuel pump relay terminal No. 4. (Scheme 37) Operate starter motor. If voltmeter indicates about 3 volts, replace relay. If voltage is not to specification, check wiring between fuel pump relay and ECU. If wiring is okay, see ELECTRONIC CONTROL UNIT - IGNITION (850).

FUEL SYSTEM

Fuel Pressure Regulator (940)

1. Connect Fuel Pressure Gauge (5011 ) between fuel line and fuel rail. Seal free end of hose with Plug (5266 ). Start fuel pumps. Lift out central electrical unit and remove system relay. (Scheme 38)
2. Connect a jumper wire between relay terminals No. 30 and 87/2. (Scheme 39) Remove fuses No. 30 and 31. (Scheme 40) Connect a jumper wire between right fuse terminals. (Scheme 40) Fuel pumps should start. Fuel filler cover can be removed to determine whether main pump is operating.
3. Fuel pressure should be 42 psi (3 kg/cm 2 ). If pressure is too low, pinch return hose by hand and check whether pressure rises. Do not allow pressure to exceed 86 psi (6 kg/cm 2 ). If pressure rises rapidly, replace pressure regulator.

Fuel Pressure Regulator (850)

1. Install Connector (998 9725 ) to Fuel Pressure Gauge (999 5011 ). Using Adapter (999 5479 ), connect pressure gauge to valve on fuel distribution manifold. Turn valve in direction of adapter. Connect other gauge connection to Fuel Drainage Unit (981 2270, 2273 and 2282 ).
2. Remove electrical distribution unit cover in engine compartment. Remove fuel pump relay. (Scheme 36) Connect jumper wire between fuel pump relay terminals No. 1 and 3. Turn ignition on. Fuel pump should start. If system pressure is 43.5 psi (300 kPa), go to step 5).
3. If system pressure is too high, remove jumper wire. Disconnect pressure regulator return and vacuum lines and blow through lines. If both lines are okay, replace regulator and recheck pressure.
4. If system pressure is too low, squeeze return line and ensure pressure rises. Do not allow pressure to exceed 87 psi (600 kPa). If pressure rises quickly, pump and line are okay. Replace pressure regulator and recheck system pressure. If pressure rises slowly, check for blocked fuel filter, fuel pump strainer or fuel lines. If pressure does not rise, replace pump.
5. If system pressure was 43.5 psi (300 kPa) in step 2), check operation of pressure regulator by connecting Vacuum Pump (999 5843 ) to pressure regulator. Apply vacuum to regulator. Ensure system pressure falls by same amount as regulator pressure.
6. Turn ignition off. Remove jumper wire between fuel pump relay terminals No. 1 and 3. Reinstall fuel pump relay. Check fuel system residual pressure. Pressure should not fall below 20 psi (200 kPa) in less than 20 minutes. If fuel pressure falls faster, check injectors, pressure regulator, and fuel pump. Disconnect Pressure Gauge (999 5011 ).

Scheme 38

Scheme 39

Scheme 40

Fuel Injectors (940 Non-Turbo With Regina Fuel Injection)

1. Remove auxiliary relay, located on left front fender panel. Jumper relay terminals No. 2 (Blue/Yellow wire) and No. 3 (Green/Red wire). Connect ohmmeter between fuel injection ECU terminals No. 9 and 18. Fuel injection terminal identification is marked on connector. Resistance should be 4 ohms. If resistance is 5.3 ohms, one injector or wire is faulty.
2. If resistance is 8 ohms, 2 injectors or wires are faulty. If resistance is 16 ohms, 3 injectors or wires are faulty. To check injectors individually, disconnect injector wires and connect ohmmeter between suspected injector terminals. Resistance should be 15-17 ohms. Replace as necessary.

Fuel Injectors (850)

1. Remove fuel injector cover. Connect an ohmmeter between injector terminals. Injector resistance should be 15.6-16.2 ohms. If not, replace injector. If resistance is okay, disconnect injector connector. Connect voltmeter between connector terminals. Operate starter motor. Voltmeter should indicate 300-700 millivolts, depending on engine temperature.
2. If voltage is not to specification, connect voltmeter between injector connector terminal No. 1 (Green wire) and ground. If battery voltage is present, see ELECTRONIC CONTROL UNIT - FUEL INJECTION (850) under COMPUTERIZED ENGINE CONTROLS.
3. If battery voltage is not present, remove main relay from engine compartment relay base. Connect voltmeter between ground and relay connector terminal No. 4, then between ground and relay connector terminal No. 2. If battery voltage is present in both instances, go to next step. If battery voltage is not present, check relay voltage supply from battery.
4. Turn ignition on. Reinstall relay in base. Relay should click. If relay does not click, see ELECTRONIC CONTROL UNIT - FUEL INJECTION (850) under COMPUTERIZED ENGINE CONTROLS.

Fuel Injectors (940 Turbo)

1. Remove auxiliary relay, located on left front fender panel. Jumper relay terminals No. 2 (Blue/Yellow wire) and No. 3 (Green/Red wire). Connect ohmmeter between fuel injection ECU terminals No. 9 and 18. Fuel injection terminal identification is marked on connector. Resistance should be 2.25 ohms. If resistance is 2.9 ohms, one injector or wire is faulty.
2. If resistance is 4.4 ohms, 2 injectors or wires are faulty. If resistance is 8.5 ohms, 3 injectors or wires are faulty. To check injectors individually, disconnect injector wires and connect ohmmeter between suspected injector terminals. Resistance should be 2 ohms. Replace as necessary.

Fuel Injectors (960)

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn ignition on.
2. Connect voltmeter between measuring unit terminals No. 17 and 24, and then between terminals No. 16 and 24. In both cases, battery voltage should be present.
3. Turn ignition off. Connect an ohmmeter between measuring unit terminals No. 37 and 17. Resistance should be about 5.3 ohms. Connect ohmmeter between measuring unit terminals No. 37 and 16. Resistance should be about 5.3 ohms.
4. Disconnect injector connectors. Using an ohmmeter, check resistance of each injector. Resistance should be 16 ohms at 68°F (20°C). Replace as necessary.

Cold Start Valve (940)

Disconnect cold start valve harness connector. Connect ohmmeter leads between cold start valve terminals. Ohmmeter should indicate 9-11 ohms. If reading is not 9-11 ohms, replace cold start valve.

IDLE CONTROL SYSTEM

Note. On 940, when measuring resistance and voltage at ECU connector, DO NOT probe into front of connector. Probe only through side of connector, just enough to make a good electrical contact. Terminal identification numbers are stamped on side of ECU connector.

IDLE AIR CONTROL VALVE (940)

1. Turn ignition switch to OFF position. Disconnect ECU connector. Remove cover from ECU connector to expose terminal identification numbers. On 940 with LH Jetronic fuel system, connect an ohmmeter between fuel injection ECU terminals No. 9 and 33.
2. Ohmmeter should read 8 ohms. On 940 with Regina fuel injection system, connect ohmmeter between fuel injection ECU terminalsNo. 9 and 33. Ohmmeter should read 4 ohms.

IDLE AIR CONTROL VALVE (850)

Ensure ignition is off. Disconnect idle air control valve connector. Connect an ohmmeter between connector terminals No. 1 (Blue/Black wire) and No. 2 (Green wire), then between terminals No. 2 (Green wire) and No. 3 (Blue/White wire). If about 10-14 ohms are not present, replace idle air control valve. If about 10-14 ohms are present, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section, see below.

1. 850 Non-Turbo, see: «TESTS W/CODES - NON-TURBO»(ref-12934)
2. 850 Turbo, see: «TESTS W/CODES - TURBO»(ref-12933)
3. 940, see: «TESTS W/CODES - LH 2.4/EZK 116 IGNITION»(ref-15203)
4. 960, see: «TESTS W/CODES»(ref-15206)

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article in the ENGINE PERFORMANCE Section.

Detonation (Knock) Sensor (940)

1. Disconnect knock sensor connector. Connect jumper wire between knock sensor terminals No. 1 and 2. (Scheme 41) Turn ignition off. Disconnect ignition ECU connector.
2. Remove cover from ECU connector to expose terminal identification numbers. Connect ohmmeter leads between terminals No. 12 and 13 of ignition ECU connector. (Scheme 34) Ohmmeter should indicate zero ohms.
3. If ohmmeter resistance is high (infinity), one or both wires may be shorted. Remove jumper wire, and take reading with ohmmeter on each wire. Replace damaged wires as required. If wires are not damaged, replace knock sensor.

Detonation (Knock) Sensors (850)

1. Connect Measuring Unit (981 3190 ) and Adapter (981 3195 ) to distributor ignition ECU. Disconnect negative battery cable. Remove ECU cover located in right front engine compartment. Remove distributor ignition ECU. Press adapter onto ECU and pull lead upward through slot beside module. Press ECU, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
2. Depending upon which knock sensor is being checked, disconnect front or rear knock sensor connector and connect a jumper wire between knock sensor connector terminals. (Scheme 41)
3. Connect ohmmeter between measuring unit terminals No. 22 and 23, or 24 and 25 (depending on which sensor is being checked). Reading should be zero ohms. If reading is correct, replace knock sensor. Tighten knock sensor to 15 ft. lbs. (20 N.m). If ohmmeter does not indicate zero ohms, check distributor ignition ECU wiring.

Detonation (Knock) Sensors (960)

1. Turn ignition off and remove fuse No. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn ignition on.
2. Depending upon which knock sensor is being checked, disconnect front or rear knock sensor connector and connect a jumper wire between knock sensor connector terminals. (Scheme 41)
3. Connect an ohmmeter between measuring unit terminals No. 2 and terminal No. 11 or 29 (depending on which sensor is being checked). Reading should be zero ohms. If reading is correct, replace knock sensor. Tighten knock sensor to 15 ft. lbs. (20 N.m).

Scheme 41

EXHAUST GAS RECIRCULATION (EGR)

Note. For additional information on EGR system, see appropriate G - TESTS W/ CODES article in the ENGINE PERFORMANCE Section, see below.

1. 850 Non-Turbo, see: «TESTS W/CODES - NON-TURBO»(ref-12934)
2. 850 Turbo, see: «TESTS W/CODES - TURBO»(ref-12933)
3. 940, see: «TESTS W/CODES - LH 2.4/EZK 116 IGNITION»(ref-15203)
4. 960, see: «TESTS W/CODES»(ref-15206)

1. Ensure all connections are tight and do not leak. Ensure all vacuum hoses are connected and not kinked. Check EGR function with cold and hot engine at different engine speeds.
2. With engine coolant temperature below 131°F (55°C), EGR valve should be closed at all engine speeds. If EGR valve is open, replace thermostat valve.
3. With coolant temperature above 140°F (60°C), EGR valve should only open at partial throttle. If EGR valve remains closed, check thermostat valve by disconnecting vacuum hose from EGR valve and blowing air into it. Air should flow freely through thermostatic valve. If air does not flow freely through thermostatic valve, replace valve.

FUEL EVAPORATIVE (EVAP)

Note. Only 850 fuel evaporative testing procedures are available from manufacturer. See VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section for information on hose routing.

Scheme 42

1. Disconnect ventilation hose and canister guide from throttle body. Connect vacuum pump to ventilation (large) port and begin pumping to obtain partial vacuum. (Scheme 42) Even though pressure returns quickly to atmosphere pressure, resistance should be felt when pumping. If vacuum and resistance are okay, go next step. If vacuum cannot be reached or resistance is not okay, check ventilation hose connected to canister for damage or leakage. If hose is okay, repeat test using new canister.
2. Apply vacuum to small vacuum port. If partial vacuum is present, go to next step. If no partial vacuum is present, check vacuum hose connected to canister for leakage. If hose is okay, repeat test using new canister.
3. Maintain vacuum in vacuum hose. Blow into hose that fits into large port. If air passes through canister with slight resistance, canister and guide are okay. If air does not pass through canister, check vacuum hose for blockage. If vacuum hose is okay, repeat test using new canister.

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

Cooling Fan Motor (850)

1. Connect Measuring Unit (981 3190 ) and Adapter (981 3195 ) to distributor ignition ECU. Disconnect negative battery cable. Remove ECU cover located in right front engine compartment. Remove distributor ignition ECU. Press adapter onto ECU and pull lead upward through slot beside module. Press ECU, with adapter connected, into connector in bottom of ECU box. Connect measuring unit to adapter 60-pin connector.
2. On vehicles without A/C, connect voltmeter between measuring unit terminals No. 20 and 17. On vehicles with A/C, connect voltmeter between measuring unit terminals No. 20 and 25. In both instances, battery voltage should be present. If battery voltage is not present, check wiring between fan motor, relay, and ground.

Cooling Fan Motor (960)

1. Turn ignition off and remove fuseNo. 24. Connect Measuring Unit (999 3070 ) between ECU and ECU connector. (Scheme 35) Turn ignition on.
2. Connect voltmeter between measuring unit terminals No. 14 and 19. Battery voltage should be present. Connect voltmeter between measuring unit terminals No. 34 and 19. Battery voltage should bepresent.
3. If no voltage is present at control unit, check voltage supply to relay. If voltage is present, check wiring between fan motor, relay and ground.