Leak Detection Pump, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test Requirements 

• The Fuel Pump (FP) -G6- OK.
• Leak Detection Pump (LDP) -V144- fuse OK.
• The ignition switched off.

Test Procedure 

-- Perform a preliminary check to verify the customer's complaint. Refer to PRELIMINARY CHECK .

-- Remove the left rear wheel housing liner. Refer to WHEEL HOUSING LINER

-- Disconnect the electrical harness connector -3-.

Checking internal resistance

-- Using aMultimeter --, check the Leak Detection Pump (LDP) -V144- for resistance as follows:

Leak Detection Pump (LDP) -V144- terminal	Specified value
-1- to -3-	640 to 720 Ω
-2- to -3-	15 to 17 Ω

If the specifications are not obtained:

-- Replace the Leak Detection Pump (LDP) --V144--. Refer to Component Locations Overview

If the specified values are obtained:

Checking voltage supply

-- 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.

-- Using a Multimeter --, check the Leak Detection Pump (LDP) --V144-- electrical harness connector terminal 3 to the Engine Control Module (ECM) -J623- connector T60, socket 45, through the the Fuel Metering Valve -N290-, for resistance.

Specified value: 1.5 Ω max

If the specification was not obtained:

-- Check the wiring for a 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 detected in the wiring and if the voltage supply was OK:

Checking output wiring

If the manufacturers test box is being used, perform the following step.

-- Connect the test box - VAG1598/42- to the wiring harness of the Engine Control Module (ECM) -J623- with adapter cable - VAG1598/39-1-. Refer to Component Locations Overview .

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

Remove the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING 

-- Using a Multimeter --, check the Leak Detection Pump (LDP) --V144-- electrical harness connector terminal 1 to Engine Control Module (ECM) -J623- electrical harness connector terminal 20 for resistance.

-- Using a Multimeter --, check the Leak Detection Pump (LDP) --V144-- electrical harness connector terminal 2 to Engine Control Module (ECM) -J623- electrical harness connector terminal 24 for resistance.

Leak Detection Pump (LDP) --V144-- electrical harness connector terminals	Engine Control Module (ECM) -J623 - electrical connector terminals or test box sockets
1	20
2	24

Specified value: 1.5 Ω max.

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 faulty wiring connection.

If no malfunction is found in wiring:

-- Replace the Engine Control Module (ECM) -J623-. Refer to ENGINE CONTROL MODULE, REPLACING 

If the specification was obtained:

-- Erase the DTC memory. Refer to 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 .

-- End diagnosis and switch ignition off.

-- Assembly is performed in the reverse of the removal.

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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .