Testing fuel pump relay and actuation: Audi 4.2 (AHK)

A - Functional test of fuel pump relay -J17

Note:

The fuel pump relay is located in the central electrics in the left hand footwell, relay position 6.

Remove shelf in front left hand footwell.
Remove the bottom trim panel from the right A pillar.
Fold back carpeting in front right footwell and unscrew cover of electronics box.

Pull out fuse from brown fuse holder (fuse for injectors).
Pull out fuse from black fuse holder (fuse for solenoid valves).

Pull out fuse 17 at the fuse holder.
Connect diode test lamp V.A.G 1527 between earth and one of the two contacts of fuse 17.
Operate starter briefly

Fuel pump relay should pick up (can be felt and heard) and diode test lamp should briefly light up.

If the fuel pump relay does not pick up, test actuation => Page
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.

If the diode test lamp does not light up, repeat the test at the other contact of fuse 17.

If the diode test lamp still does not light up:

Remove fuel pump relay from relay position 6.
Test wiring connection from fuse 17 to contact 30 at relay position 6 for continuity.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Connect diode test lamp V.A.G1527 between earth and contact 1 of the fuse (from the brown fuse holder).
Switch ignition on.

The diode test lamp should light up.

If the diode test lamp does not light up, repeat the test at contact 2 of the fuse.

If the diode test lamp still does not light up:

Test wiring connection from fuse (from brown fuse holder) to contact 31 at relay position 6 for continuity.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Connect diode test lamp V.A.G1527 between earth and contact 1 of the fuse (from the black fuse holder).
Operate starter briefly

Fuel pump relay should pick up (can be felt and heard) and diode test lamp should light up.

If the diode test lamp does not light up, repeat the test at contact 2 of the fuse.

If diode test lamp still does not light up, test wiring connection from fuse (from black fuse holder) to contact 30 at relay position 6 for continuity.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

B - Testing voltage supply and actuation of fuel pump relay

Pull out fuel pump relay -J17 from the central electrics, relay position 6.

Testing voltage supply

Switch ignition on.
Connect handheld multimeter V.A.G 1526 in turn between contacts 28 (positive, terminal 15) and 34 (earth), and 32 (positive, terminal 30) and 34 (earth) of the relay base.

Specification: approx. battery voltage in each case

If battery voltage is not present, check the wiring for open circuit.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

Testing actuation

Connect diode test lamp V.A.G 1527 with adapter cable set 1594 between contacts 28 (positive) and 29 (earth, actuation of engine control unit -J220).
The diode test lamp should come on for about 1 sec when the ignition is switched on, and then go out again. The diode test lamp should light up and remain lit when the starter is operated.

Note:

Diode test lamps with a low current consumption do not go out completely after 1 sec, but continue to glow faintly until the starter is operated.

If the diode test lamp does not light up, test the wiring as follows:

Connect test box V.A.G 1598/19 to wiring harness of engine control unit =>Page
24-14
.

Connect handheld multimeter V.A.G 1526 between contact 29 of the relay base and socket A4 of the test box, and check the wiring for continuity.
If the specified value is not attained, check the wiring for open circuit.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

If there is no open circuit and the diode test lamp still does not light up, fit a new engine control unit
=> Page
24-15
If the actuation of the fuel pump relay and the wiring are OK, replace the fuel pump relay.
Refit the fuses.