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 => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

Start diagnosis

- Remove the right rear wheel housing liner. Refer to Exterior Equipment

- 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 Secondary Air Injection (AIR) Pump Relay (J299).

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









- Operate the starter briefly.

Specified value: battery voltage.

- Switch the ignition off.

If the specified value was not obtained:

- Check the Leak Detection Pump (LDP) (-V144-) electrical harness connector terminal 3 to the Secondary Air Injection (AIR) Pump Relay (J299) socket T31/25 for an open circuit or a short circuit to Battery positive (+).

- 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 the voltage supply was OK:

Checking wiring

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

- Install the Adapter Cable (121-pin) (VAG1598/31)

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

- Remove the Motronic Engine Control Module (ECM) (J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter, check the Leak Detection Pump (LDP) (-V144-) electrical connector to the Motronic Engine Control Module (ECM) (J220) electrical harness connector T121 for resistance.









Specified value: 1.5 ohms max.

If the specification is not obtained:

- Check the wiring for an open circuit, 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 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 DTC returns, replace the Motronic Engine Control Module (ECM) (J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End of diagnosis.

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 ] Readiness Code.