Leak Detection Pump, Checking

Leak Detection Pump, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuse (SB6) OK.

• The Motronic Engine Control Module (ECM) Power Supply Relay (J271) OK.

• The ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Diagnostic Mode 09 - Read Vehicle Information.

- Remove the left rear wheel housing liner.

Start diagnosis

- Disconnect the Leak Detection Pump (LDP) (V144) electrical harness connector - 3 -.





Checking internal resistance

- Using a Multimeter, check the Leak Detection Pump (LDP) (V144) for resistance as follows:










If any of the specifications are not obtained:

- Replace the Leak Detection Pump (LDP) (-V144-).

If the specified values are obtained:

Checking voltage supply

• The voltage for the Leak Detection Pump (LDP) (-V144-) is supplied by the Motronic Engine Control Module (ECM) Power Supply Relay (J271) OK.

- Using a Multimeter, check the Leak Detection Pump (LDP) (-V144-) electrical harness connector terminal 3 for voltage.










- Operate the starter briefly.

Specified value: battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Using a Multimeter, check the Leak Detection Pump (LDP) (-V144-) electrical harness connector terminal 3 to the Motronic Engine Control Module (ECM) Power Supply Relay (J271) socket 2/87 for resistance.





Specified value: 1.5 ohms max

If the specification was not obtained:

- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

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

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

Checking 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) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter, check the Leak Detection Pump (LDP) (-V144-) electrical harness connector terminal 1 to Engine Control Module (ECM) (J623) electrical harness connector T81 terminal 80 for resistance.

- Using a Multimeter, check the Leak Detection Pump (LDP) (-V144-) electrical harness connector terminal 2 to Engine Control Module (ECM) (J623) electrical harness connector T81 terminal 25 for resistance.










Specified value: 1.5 ohms max.

If the specification is not obtained:

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

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

- If necessary, repair the faulty wiring connection.

If no malfunction is found in wiring:

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code Description ] Diagnostic Mode 09 - Read Vehicle Information.

- End diagnosis.

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

- Replace the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

Final procedures

After the 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 ] Engine.

End of diagnosis