Leak Detection Pump (LDP), Checking

Leak Detection Pump (LDP), Checking

Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test requirements







- Corresponding fuses on E-box in engine compartment, left side, for Leak Detection Pump (LDP) -V144- must be OK.

NOTE: Fuses on this fuse holder are labelled "SB" in the wiring diagram.

- Engine Component Power Supply Relay -J757-, relay position R3, must be OK, check.
- Ground (GND) connections between engine and chassis must be OK.
- Ignition switched off.

Test sequence
Observe safety precautions.
Observe rules for cleanliness.

- Remove right rear wheelhousing liner.







- Disconnect 3-pin connector of Leak Detection Pump (LDP) -V144- (arrow).

Checking resistance







- Check resistance between terminals 1 and 3 of diagnostic pump.

Specified value: 640 to 720 Ohms

- Check resistance between terminals 2 and 3 of diagnostic pump.

Specified value: 12.0 to 20.0 Ohms

If specified values are not obtained:
- Replace Leak Detection Pump (LDP) -V144-
- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If specified values are obtained:
- Check wires to Engine Control Module (ECM) according to wiring diagram.

Checking wires to Engine Control Module (ECM)
- Connect test box to 94-pin connector of wiring harness. Test Box, Connecting For Wiring Test

Engine Control Module (ECM) is not connected.







- Check wires between test box and 3-pin connector to Engine Control Module (ECM) for open circuit according to wiring diagram.

Terminal 1 + socket 40
Terminal 2 + socket 8

Wire resistance: max. 3.0 Ohms

- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: Infinity Ohms

- Check wire between 3-pin connector terminal 3 and Engine Component Power Supply Relay -J757- for open circuit according to wiring diagram.

Wire resistance: max. 3.0 Ohms

- Erase DTC memory of Engine Control Module (ECM). Diagnostic Mode 04 - Erase DTC Memory
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If no malfunctions are found in wires:
- Replace Engine Control Module (ECM) -J623-.