Audi Workshop Service and Repair Manuals

Note:

→ The fuel pump relay is located in the central electrics in the left-hand footwell, relay position 4.

Special tools, testers and auxiliary items

• ◆ Hand multimeter V.A.G 1526 or V.A.G 1526 A
• ◆ Diode test lamp V.A.G 1527
• ◆ Adapter set V.A.G 1594
• ◆ Test box V.A.G 1598/22

A - Testing fuel pump relay -J17

• ‒ Remove storage bin in front left-hand footwell.
• ‒ → Remove fuse 28 from fuse holder and connect diode test lamp V.A.G 1527 between earth and one of the two contacts for fuse 28.
• ‒ Operate the starter briefly.

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

• ‒ If the fuel pump relay picks up but the diode test lamp does not light up, repeat the test on the other contact.

• ‒ → If the diode test lamp still does not light up, test for open circuits in the wiring between fuse 28 and contact 23 in relay position 4.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ If no open circuit is detected, fit a new fuel pump relay.
• ‒ If the fuel pump relay does not pick up, test activation
  .
• ‒ If the power supply and activation are OK, fit a new fuel pump relay.

B - Testing power supply and activation of fuel pump relay

• ‒ Remove fuel pump relay -J17 from central electrics, relay position 4.

Testing power supply

• ‒ Switch ignition on.

• ‒ → Connect hand-held multimeter V.A.G 1526 first to contact 19 (positive) and earth on relay panel, then to contact 17 (positive) and earth on relay panel.

Specification: approx. battery voltage in each case

• ‒ If the values are not as specified, rectify the open circuit.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

Testing activation

• ‒ → Connect diode test lamp V.A.G 1527 to contact 16 (earth) and positive.
• ‒ The diode test lamp should light up and remain lit when the starter is operated.

Note:

Diode test lamps with a low current draw do not go out completely 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 1598/22 to wiring harness for engine control unit.
  .

• ‒ Connect hand-held multimeter between contact 16 on relay panel and socket 4 on the test box, then test wiring for open circuits.
• ‒ Rectify any open circuits.

=> Current flow diagrams, Electrical fault finding and Fitting locations binder

• ‒ If there is no open circuit and the diode test lamp does not light up, fit a new engine control unit => Page 24-10.
• ‒ If both the fuel pump relay activation and the wiring are OK, fit a new fuel pump relay.
• ‒ Refit fuse 28.