With Manufacturer's Scan Tool

Diesel Direct Injection System Voltage Supply, Checking

Special tools and equipment
- Test box VAG 1598/31
- Hand multimeter VAG 1526 or multimeter VAG 1715
- Adapter set VAG 1594
- Wiring diagram

Check conditions







- The fuses must be OK.
- The battery voltage must be at least 11.5 V.
- All electrical accessories, e.g. lights and rear window heating must be switched off.
- A/C switched off.
- Alternator OK, checking.

Test sequence
- Switch off ignition.
- Remove wiper arms and plenum cover.







- Connect test box VAG 1598/31 to control unit and wiring harness.
- Measure voltage between following sockets:
1/2 and 4/5
37 and 4/5
Specification: Approx. 0 V

- Switch on ignition.
- Again measure voltage between sockets:
1/2 and 4/5
37 and 4/5
Specification approx. battery voltage

If the specifications are not obtained:
- Check voltage supply relay terminal 30 -J317-.
- Check wiring connections for open circuit, short circuit and transfer resistance at contacts according to wiring diagram.

If wiring and relay are ok:
- Replace Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248-.