Leak Detection Pump (LDP) -V144-, Checking

Leak Detection Pump (LDP) -V144-, Checking







Special tools and equipment
- VAG1526A Multimeter
- VAG1527B Voltage tester
- VAG1594A Adapter set
- VAG1598/31 Test box
- VAS5051 Vehicle diagnosis, testing and information system

Requirements
- Ignition on







- VAS 5051 tester connected and "01 Engine electrical" selected

Checking function







Display on VAS 5051:
- Click on diagnostic function -1- "03 Output check diagnosis"
- Click -> button until leak detection pump is activated.
- Leak Detection Pump (LDP) -V144- will be activated for approximately 1 minute.

NOTE: Operating noise of Leak Detection Pump (LDP) is audible at front right wheelhousing.

- Click <- button to end the function "03-Output check diagnosis"
- Select 06 End sequence.
- Switch ignition off.

If LDP is not activated (no audible operating noise):
- Remove Leak Detection Pump (LDP) -V144-, and disconnect harness connectors.

Checking internal resistance







- Connect multimeter for resistance measurement as follows.

Leak Detection Pump Specified value
LDP) -V144- terminals
1 + 3 640-720 Ohms
2 + 3 15-17 Ohms

If specified values are not obtained:
- Replace Leak Detection Pump (LDP) -V144-

If specified values are obtained:
- Check voltage supply at harness connector of Leak Detection Pump (LDP)

Checking voltage supply

NOTE: Voltage supply for the Leak Detection Pump (LDP) runs via the Fuel Pump (FP) relay.

Requirement
- Fuse for Leak Detection Pump (LDP) OK
- Disconnect connector at Leak Detection Pump (LDP).







- Connect VAG1527B voltage tester as follows:

Electrical harness Measure to
connector terminal
3 Engine Ground (GND)

- Operate starter briefly.
- LED must light

If LED does not light:







- Check electrical wire connection from terminal 3 via fuse to Fuel Pump (FP) relay for open circuit.

- Repair open circuit if necessary.

Checking output wire







- Connect VAG1527B voltage tester as follows:

Electrical harness Measure to
connector terminal
2 Battery +

- Initiate output Diagnostic Test Mode
- LED must blink.

If LED does not blink:
- Click <- button to end function "03 Output check diagnosis"
- Select "06 End sequence"
- Switch ignition off.







- Connect VAG1598/31 test box to connector of wiring harness. Engine Control Module (ECM) must not be attached. Ground (GND) clip (arrow) at test box must be clipped to battery negative terminal (arrow).







- Check following wire connection for open circuit and short circuit to Ground (GND) and B+:

Electrical harness VAG1598/31 test
connector terminal box socket
2 25

- Repair open circuit or short circuit if necessary.

If no malfunctions are found, but Leak Detection Pump (LDP) does not function during output Diagnostic Test Mode (DTM):
- Replace Leak Detection Pump (LDP) -V144-
- Observe safety precautions after re-connecting Engine Control Module (ECM).

Checking input wire
- Switch ignition off.







- Connect VAG1598/31 test box to connector of wiring harness. Engine Control Module (ECM) must not be attached. Ground (GND) clip (arrow) at test box must be clipped to battery negative terminal (arrow).







- Check following wire connection for open circuit and short circuit to Ground (GND) and B+:

Electrical harness VAG1598/31 test
connector terminal box socket
1 80

- Repair open circuit or short circuit if necessary.
- Observe safety precautions after re-connecting Engine Control Module (ECM).
- Generate readiness code.