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







- Fuses in E-box (in plenum chamber, left) must be OK:
- Motronic Engine Control Module (ECM) Power Supply Relay - J271 - -position A3- must be OK, check:
- Ground (GND) connections between engine and chassis must be OK.
- Ignition switched off.

Test sequence
- Remove rear right wheelhousing liner.







- Disconnect 3-pin connector of Leak detection pump (LDP) - V144 - (-2-).


Checking resistances







- Measure resistance between terminals 1 + 3 of diagnostic pump.

Specified value: 640 to 720 ohms.

- Measure resistance between terminals 2 + 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 according to wiring diagram.

Checking wiring
- Connect test box to control module wiring harness. Connecting Test Box For Wiring Test







- Check wires between test box and 3-pin connector for open circuits according to wiring diagram.
Terminal 1+socket 80
Terminal 2+socket 25

Wire resistance: max. 1.5 ohms.

- Also 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 Motronic Engine Control Module (ECM) Power Supply Relay - J271 - for open circuit according to wiring diagram

Wire resistance: max.m 1.5 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 Motronic Engine Control Module (ECM) - J220 -.