Leak Detection Pump: Testing and Inspection

Leak Detection Pump (LDP), Checking

Special tools and equipment
- Fluke 83 Multimeter
- VAG 1527 B Voltage tester
- VW 1594 Adaptor kit
- Wiring diagram

Function test
- Initiate Output Diagnostic Test Mode (DTM) and select EVAP Canister Purge Solenoid Valve -N115-

During DTM, Control Module for Fuel System Diagnosis -J490- and Leak Detection Pump (LDP) are triggered. By touching LDP you can feel whether the pump works.

Electrical test







- Disconnect 3-pin connector -1- from LDP.
- Switch Fluke 83 multimeter to resistance range.
- Connect multimeter between terminals 1 and 3 of LDP.
- Specification: 640 to 720 Ohms
- Connect multimeter between terminals 2 and 3 of LDP.
- Specification: 17.5 to 27.5 Ohms.

If specifications not obtained:
- Replace Leak Detection Pump -V144-.

Voltage supply, checking

Requirement







- Fuse 29 -arrow- OK







- Disconnect 3-pin connector -1- from LDP.
- Connect VAG 1527 B Voltage tester between connector terminal 3 (positive) and engine Ground.
- Start engine and let idle.
- LED must light up.

If LED does not light up:
- Check wiring between connector terminal 3 and central electric for open circuit using Wiring diagram, repair as necessary.
- Switch ignition OFF.

Wiring, checking







- Connect VW 1594/18 Test box to wiring harness for control module.







- Check wiring between test box and 3-pin connector for open circuit according to wiring diagram.
Terminal 1 + socket 46
Terminal 2 + socket 35
- Specification: max. 1.5 Ohms

- Also check wiring for short circuit one against the other.
Terminal 3 + socket 35
Terminal 3 + socket 46
Terminal 2 + socket 46
- Specification: Infinity Ohms

If you do not find a wiring malfunction:
- Replace LDP -V144-.