Leak Detection Pump (LDP) V144 , checking

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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 .

Fig 1: Locating Leak Detection Pump V144 Electrical Harness Connector

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Checking internal resistance

Fig 2: Locating 3-Pin Connector At Fuel System Leak Detection Pump V144

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

NOTE:

The voltage for the Leak Detection Pump (LDP) -V144- is supplied by the Fuel Pump (FP) Relay J17.

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

Fig 3: 3-Pin Electrical Harness Connector & Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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:

Fig 4: 3-Pin Electrical Harness Connector & Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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.

Fig 5: 3-Pin Electrical Harness Connector & Terminals

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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:

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

End diagnosis