Fuel Pump Relay: Testing and Inspection

Checking fuel pump relay

- Remove console in left front footwell.
- Unfasten passenger-side A-pillar lower trim.
- Fold back carpet in right front footwell.
- Remove cover from electronics box.
- Remove Heated Oxygen Sensor (HO2S) circuit breaker -S73-.
^ Located in yellow holder in auxiliary relay carrier tube (on A-pillar, right).

Central Electronics Box:

- Remove the following:
^ Evaporative Emission (EVAP) frequency valve circuit breaker -S75- (position -1-, black holder).
^ Injector valve circuit breaker -S72- (position -2-, brown holder).
- Remove fuse 17 from fuse holder.
- Connect LED tester US 1115 or equivalent between Ground (GND) and either terminal of fuse 17, using adapter cables from connector test kit VW 1594.
- Operate starter briefly.
^ Fuel pump must begin running
^ LED tester must light up

If fuel pump does NOT activate:
- Check control signal.

If LED tester does NOT light up:
- Repeat test on other terminal of fuse 17.

Central Electric Panel With Detail Of Relay Position 6:

If LED tester still does NOT light up
- Check continuity (according to wiring diagram) between fuse 17, and terminal 30 (central electric panel relay position 6).
- Repair or replace wiring, as necessary.

Fuse Holder:

- Connect LED tester between GND and terminal -1- of black holder EVAP frequency valve circuit breaker -S75-.
- Operate starter briefly.
^ Fuel pump relay must be activated
^ LED tester must light up

If LED tester does NOT light up:
- Connect LED tester to terminal -2- of circuit breaker holder, and repeat test.

Central Electric Panel With Detail Of Relay Position 6:

If LED tester still does NOT light up
- Check continuity between circuit breaker and terminal 31 (central electric panel relay position 6), using wiring diagram.
- Repair open circuit, as necessary.

Fuse Holder:

- Connect LED tester between GND and terminal -1- of brown fuse holder for injector valve circuit breaker -S72-.
- Operate starter briefly.
^ Fuel pump relay must be activated
^ LED tester must light up

If LED tester does NOT light up:
- Connect LED tester to terminal 2 of circuit breaker and repeat test.

Central Electric Panel With Detail Of Relay Position 6:

If LED tester still does NOT light up:
- Check continuity (according to wiring diagram) between circuit breaker and terminal 31 (central electric panel relay position 6).
- Repair open circuit, as necessary.

Fuse Holder:

- Connect LED tester between GND and terminal 1- of yellow holder for Heated Oxygen Sensor (HO2S) circuit breaker -S73-.
^ Located in auxiliary relay holder 2, on A-pillar, right
- Operate starter briefly.
^ Fuel pump relay must be activated
^ LED tester must light up

If LED tester does NOT light up:
- Connect LED tester to terminal 2, and repeat test.

Central Electric Panel With Detail Of Relay Position 6:

If LED tester still does NOT light up:
- Check continuity between circuit breaker holder and terminal 30 of central electric panel relay position 6, using wiring diagram.
- Repair or replace wiring, as necessary.

Checking fuel pump relay control signal

- Remove fuel pump relay from central electric panel (relay position 6).
- Switch ignition ON.

Central Electric Panel With Detail Of Relay Position 6:

- Connect Digital Volt Ohm Multimeter (DVOM), in turn, between:
^ Relay connector terminals 28 and 34
^ Relay connector terminals 32 and 34
^ Readings must be approximately 12 volts each

If NO:
- Repair or replace wiring as necessary, according to wiring diagram.
- Connect LED tester US 1115 or equivalent between terminals 28 and 29.
- Switch ignition ON.
^ LED tester must light up dimly, then become visibly brighter while cranking starter.

If LED tester lights up dimly when ignition is switched ON, but does NOT become brighter while cranking starter:
- Replace Engine Control Module (ECM).

If LED tester does NOT light up:
- Check wiring as follows:
- Connect VAG 1598 Test Box (using VAG 1598/5 adapter cable) only to harness connector of ECM. Refer to VAG 1598 Pin Out Box Connecting Connecting and Testing VAG 1598 Pin Out Box

Engine Control Module Harness Connector:

- Check continuity between: terminal 28 of relay position 6, and terminal 3 of Test Box.
^ Must be 1 ohm maximum

If NO:
- Repair or replace wiring.

If wiring is OK but LED tester does NOT light up:
- Replace ECM.
- Re-install circuit breakers -S73., -S75-, -S72- and fuse 17.