Leak Detection Pump V144, Checking

Leak Detection Pump V144, Checking

Special tools, testers and auxiliary items required
- Multimeter.
- Wiring diagram.

Test requirements
- Fuse SB44 OK.
- The ignition switched off.

NOTE: The voltage for the Leak Detection Pump (LDP) -V144- is supplied by the Motronic Engine Control Module (ECM) Power Supply Relay 2 J670.

Test procedure
- Perform a preliminary check to verify the customers complaint. Preliminary Check

Start diagnosis
- Remove the right rear wheel housing liner.







- 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:

Leak Detection Pump (LDP) V144 Specified value
electrical connector terminals
1 + 3 640 to 720 Ohms
2 + 3 15 to 17 Ohms

If the specifications was not obtained:
- Replace the Leak Detection Pump (LDP) -V144-.

If the specified values are obtained:

Checking voltage supply







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

Leak Detection Pump (LDP) -V144- Measure to
electrical harness connector terminal
3 Engine Ground (GND)

- Operate the starter briefly.

Specified value: battery voltage.
- Switch the ignition off.

If the specified value was not obtained:
- Check the wiring connection from the Leak Detection Pump (LDP) -V144- electrical harness connector terminal 3 to the Motronic Engine Control Module (ECM) Power Supply Relay 2 J670 terminal 2/87 for an open circuit or a short circuit to Ground (GND).
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the wiring connection.

If the specified value was obtained:

Checking output 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.
- Using a Multimeter, check the Leak Detection Pump (LDP) -V144- electrical connector terminal 1 to Motronic Engine Control Module (ECM) J623 electrical connector T94 terminal 40 for an open circuit.







- Using a Multimeter, check the Leak Detection Pump (LDP) -V144- electrical connector terminal 2 to Motronic Engine Control Module (ECM) J623 electrical connector T94 terminal 8 for an open circuit.

Leak Detection Pump (LDP) Motronic Engine Control Module
-V144- electrical connector (ECM) J623 electrical connector
terminals T94 terminals or test box socket
1 40
2 8

Specified value: 1.5 Ohms.

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 wiring connection.
- Erase the DTC memory. Diagnostic Modes 01 - 09.
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- 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.
- Assembly is performed in the reverse of the removal.

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

1. Check the DTC memory. Diagnostic Modes 01 - 09
2. If necessary, erase the DTC memory. Diagnostic Modes 01 - 09
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of Diagnosis