Fuel Pump Relay, Checking

Fuel Pump Relay, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• wiring diagrams.

Test requirements

• Fuse (S163) OK.

• Load Reduction Relay (J59) OK.

• The Engine Control Module (ECM) (J623)Fuse (S229) and Fuse (S10) OK.

• The Ground (GND) connections at the engine and transmission OK.

• The battery voltage at least 12.5 V.

• The generator OK.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Using a Multimeter, check the following wiring connection for voltage.






Specified value: 12.5 V

If the specified value was not obtained:

- Check the Fuel Pump (FP) Relay (J17) socket 1/30 to the Battery for an open circuit or short to Ground (GND).

- Check the electrical harness connectors for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

- Using a Multimeter, check the following wiring connection for voltage.






- Crank the engine.

Specified value: 12.5 V

- Switch the ignition off.

If the specified value was not obtained:

- Check the Fuel Pump (FP) Relay (J17) socket 3/86 to the fuse SC 2 for an open circuit or short to Ground (GND).

- Check the electrical harness connectors for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking Ground (GND)

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 wiper arms and plenum chamber cover. Refer to the appropriate service information.

- Disconnect the Engine Control Module (ECM) (J623) electrical harness connector T121. Refer to the appropriate service information.

- Using a Multimeter, check the following wiring connection for resistance.






Specified value: 1.5 ohms.

If the specified value was not obtained:

- Check the Fuel Pump (FP) Relay (J17) socket 4/85 to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T121 terminal 65 for an open circuit or a short to Battery (+).

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

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring and the voltage supply was OK:

- Replace the Fuel Pump (FP) Relay (J17).

- Perform a road test to verify repair.

If the fault does not return:

Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.

If the fault does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the appropriate service information.

- Assembly is performed in the reverse of the removal.

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 Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

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