Fuel Injectors, Checking

Fuel Injectors, Checking

Fuel Injectors

The following test procedure is used to diagnose the five fuel injectors controlled by the Engine Control Module (ECM) (J623).

Special tools, testers and auxiliary items required

• Multimeter.

• Diode test lamp (12V).

• Wiring diagram.

Test requirements

• The Engine Control Module (ECM) (J623) fuses OK.

• The Engine Speed (RPM) Sensor (G28) OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

- Observe safety precautions.

- Observe rules for cleanliness.

Procedure

- Remove the intake manifold.

- Disconnect the Fuel Injector electrical harness connector - arrow - from the Fuel Injector to be tested.





Checking internal resistance

- Using a multimeter, check terminals 1 to 2 of the Fuel Injector to be tested for resistance.





Specified value: 12.0 to 20.0 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the faulty Fuel Injector

If the specified value was obtained:

Checking activation

- Connect a diode test lamp (12V) to the Fuel Injector electrical harness connector terminals 1 and 2 of the Fuel Injector to be tested.





- Operate the starter and test the activation of the Fuel Injector.

LED should flicker.

- Switch the ignition off.

If LED flickers:

- Replace the faulty Fuel Injector

If LED does not flicker:

Checking activation and wiring

If the manufacturers test box is being used. Perform the following step.

- Install the test box.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Motronic Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

- Using a Multimeter, check the electrical harness connector terminals of the Fuel Injector to be tested to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T60a terminals for an open circuit.





Specified value: 1.5 ohms Max.

If the specification is not obtained:

- Check the wiring for a short circuit to each other, Battery (+), Ground (GND), or an open circuit.

- Check the electrical harness connector for damage, corrosion, lose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

Assembly is performed in the reverse order of removal.

- Install the intake manifold.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.

Fuel Injectors

The following test procedure is used to diagnose all fuel injectors controlled by the Engine Control Module (ECM) 2 (J624).

Special tools, testers and auxiliary items required

• Multimeter.

• Diode test lamp (12V).

• Wiring diagram.

Test requirements

• The Engine Control Module (ECM) 2 (J624) fuses OK.

• The Engine Speed (RPM) Sensor (G28) OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

- Observe safety precautions.

- Observe rules for cleanliness.

Procedure

- Remove the intake manifold.

- Disconnect the Fuel Injector electrical harness connector - arrow - from the Fuel Injector to be tested.





• Right bank shown. Left bank similar.

Checking internal resistance

- Using a multimeter, check terminals 1 to 2 of the Fuel Injector to be tested for resistance.





Specified value: 12.0 to 20.0 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the faulty Fuel Injector

If the specified value was obtained:

Checking activation

- Connect a diode test lamp (12V) to the Fuel Injector electrical harness connector terminals 1 and 2 of the Fuel Injector to be tested.





- Operate the starter and test the activation of the Fuel Injector.

LED should flicker.

- Switch the ignition off.

If LED flickers:

- Replace the faulty Fuel Injector

If LED does not flicker:

Checking activation and wiring

If the manufacturers test box is being used. Perform the following step.

- Install the test box.

If the manufacturers test box is not being used. Perform the following step.

- Remove the Engine Control Module (ECM) 2 (J624). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

- Using a Multimeter, check the electrical harness connector terminals of the Fuel Injector to be tested to the Engine Control Module (ECM) 2 (J624) electrical harness connector T60b terminals for an open circuit.





Specified value: 1.5 ohms Max.

If the specification is not obtained:

- Check the wiring for a short circuit to each other, Battery (+), Ground (GND), or an open circuit.

- Check the electrical harness connector for damage, corrosion, lose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Replace the Engine Control Module (ECM) 2 (J624). Refer to => [ Engine Control Module, Removing and Installing ] Engine Control Module, Removing and Installing.

Assembly is performed in the reverse order of removal.

- Install the intake manifold.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.