Leak Detection Pump (LDP) V144 , checking

Special tools, testers and auxiliary items required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Leak Detection Pump (LDP) V144 fuse OK.
• The Fuel Pump (FP) Relay J17 OK.
• The ignition switched off.

Test procedure 

• Perform a preliminary check to verify the customers complaint. Refer to → Motronic Engine Control Module (ECM) J220 , replacing 

Start diagnosis 

• Remove the right rear wheel housing liner. Refer to 66 EXTERIOR EQUIPMENT .

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

Checking internal resistance 

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

Leak Detection Pump (LDP) V144 electrical harness connector terminals	Specified values
1 + 3	640 to 720 Ω
2 + 3	12.5 to 19.5 Ω

If any of the specifications are not obtained:

• Replace the Leak Detection Pump (LDP) -V144-. Refer to 20 - FUEL SUPPLY .

If the specified values are obtained:

Checking voltage supply 

• Check the Leak Detection Pump (LDP) -V144- for voltage.

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

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

• 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 Fuel Pump (FP) Relay J17 terminal 23/87 for an open circuit.

Specified value: Wire resistance max 1.5 Ω.

If the specification is not obtained:

• Check the wiring for a short circuit to Battery positive (+) or an open circuit.
• Check the electrical harness connector for damage, corrosion, lose 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 Test Box 105 Pin VAG1598/31. Refer to 24 MULTIPORT FUEL INJECTION (MFI) for Engine Code AWD and 24 MULTIPORT FUEL INJECTION (MFI) for Engine Codes AWP and AWW .

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

• Remove the Motronic Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , replacing  .
• Using a Multimeter , check the Leak Detection Pump (LDP) -V144- electrical connector terminal 1 to Motronic Engine Control Module (ECM) J220 electrical connector T121 terminal 40 for an open circuit.

• Using a Multimeter , check the Leak Detection Pump (LDP) -V144- electrical connector terminals to the Motronic Engine Control Module (ECM) J220 electrical connector T121 terminals for an open circuit.

Leak Detection Pump (LDP) -V144- electrical harness connector terminals	Motronic Engine Control Module (ECM) J220 electrical harness connector T121 terminals or test box socket
1	80
2	25

Specified value: 1.5 Ω max.

If the specification is not obtained:

• Erase the DTC memory. Refer to → Diagnostic Mode 04: Reset/delete diagnostic data 
• Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to →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 MFI Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , replacing  .
• Assembly is performed in the reverse of the removal.

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

• Install the right rear wheel housing liner. Refer to 66 EXTERIOR EQUIPMENT .

Final procedures 

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

1. Check the DTC memory.
2. If necessary, erase the DTC memory.
3. If the DTC memory was erased, generate readiness code.

End diagnosis