Audi Workshop Service and Repair Manuals

Notes:

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

A - Operational test of fuel pump relay -J17

• ‒ Pull out fuses 28, 29 and 34.
• ‒ Connect diode test lamp V.A.G 1527 to the relevant front contact for fuse 28 / 29 / 34 and operate the starter for a few seconds - the fuel pump relay should pick up (can be felt and heard) and the diode test lamp should light up.

• ‒ If the diode test lamp does not come on although the fuel pump relay picks up, repeat test at the rear contact of the relevant fuse.

• ‒ → If the diode test lamp still fails to come on, check the wiring between contact 30 at relay position 6 and fuse 28 / 29 and between contact 31 and fuse 34 for continuity according to the current flow diagram - rectify any open circuit(s) as necessary.
• ‒ If no open circuit is detected, replace the fuel pump relay.
• ‒ If the fuel pump relay does not pick up, test actuation =>Page 24-34.
• ‒ If the voltage supply and the actuation are OK replace fuel pump.

B - Testing power supply and actuation of fuel pump relay

• ‒ Remove fuel pump relay -J17 from the central electronics, relay position 6.

Checking power supply

• ‒ Switch ignition on.

• ‒ → Connect handheld multimeter V.A.G 1526 in turn between contacts 28 (positive, terminal 15) and 34 (ground), and 32 (positive, terminal 30) and 34 (ground) of the relay base.
  Specified value: approx. battery voltage in each case
• ‒ If the specified values are not achieved, rectify the open circuit according to the current flow diagram and if necessary replace the central electrics.

Checking actuation

• ‒ → Connect diode test lamp V.A.G 1527 between contact 28 (positive) and 29 (ground actuation of Motronic control unit).
• ‒ The diode test lamp should light up when the starter is operated.

Note:

Diode test lamps with a low current draw glow faintly when the ignition is switched on and then light up more brightly when the starter is operated.

If the diode test lamp does not light up when the starter is operated, test the wiring as follows:

• ‒ Connect test box V.A.G 1598/19 to the wiring harness of the Motronic control unit.
• ‒ → Connect a hand-held multimeter between contact 29 of the relay base and socket D6 of the test box and check the wiring for continuity.

• ‒ If desired value is not attained, eliminate open circuit or short circuit according to the current flow diagram.
• ‒ If there is no open circuit and the diode test lamp still does not light up, replace the Motronic control unit.
• ‒ If the actuation of the fuel pump relay and also the wiring are OK, replay the fuel pump relay.
• ‒ Put fuses 28,29 and 34 back in.