Leak Detection Pump, Checking

Leak Detection Pump, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagram

Test requirements

• The Leak Detection Pump (LDP) (V144) fuse OK.

• The ignition switched off.

Test procedure

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

Start diagnosis

- Remove the right rear wheel housing liner.

- Disconnect the electrical harness connector - 3 -.

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





Checking internal resistance

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









If the specifications are not obtained:

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

If the specified values are obtained:

- Check the voltage supply of the Leak Detection Pump (LDP) (-V144-).

Checking voltage supply

• The voltage for the Leak Detection Pump (LDP) (-V144- ) is supplied by the Engine Control Module (ECM) (J623).

- Using the Multimeter, check the electrical harness connector for voltage.









- Turn the key on.

Specified value: approx. battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Using a Multimeter, check electrical harness connector terminal - 3 - between Leak Detection Pump (LDP) (V144) and connector T-40 cavity 21 for open circuit.





Specified value: Wire resistance max 1.5 ohms.

If the specification is not obtained:

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

- If necessary, repair the faulty wiring connection.

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

Checking output wiring

- Install the Adapter Cable (121 Pin) (VAG1598/31 ). Refer to Engine Mechanical, Fuel Injection & Ignition, Repair Group 24.

- Using a Multimeter, check the following wire connections for an open circuit.









Specified value: Wire resistance max 1.5 ohms.

If the specification is not obtained:

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

- If necessary, repair the wiring connection.

- 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 ] Readiness Code.

- End diagnosis.

If the DTC 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 => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

Assembly is performed in the reverse order of the removal, note the following:

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, Setting ] Readiness Code, Setting.

End of diagnosis.