Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31
• ◆ VAS 5051 with VAS 5051/1

Fitting location => Fitting locations overview, Page 24-5

The fuel pump and certain components of the injection system are supplied with power by way of the fuel pump relay -J17.

The fuel pump relay -J17 is only energised when the engine is running, i.e. the relay is only connected to earth (via the engine control unit) when engine speed pulses are detected in the engine control unit.

Test requirements:

• ● Battery voltage at least 12.7 V

Functional check of fuel pump relay

• ‒ Remove driver's storage compartment.

=> General Body Assembly, Interior; Repair group 68; Storage compartments, covers; Removing driver's storage compartment

• ‒ Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in the selection. For this purpose, the ignition must be switched on.

• ‒ Initiate final control diagnosis and actuate ACF solenoid valve -N80.

• ‒ → Fuel pump relay (in the central electrics, passenger's footwell on the left, position 4) should respond and fuel pump should run.
• Exit the function "03 - Final control diagnosis" by pressing the ◂ key.

A - If relay does not respond:

• ‒ Check voltage supply of fuel pump relay => Page 24-84.
• ‒ Check actuation of fuel pump relay
  .

B - If relay is responds but fuel pump does not run:

• ‒ Check voltage supply for fuel pump and components (via fuel pump relay) .

Checking voltage supply of fuel pump relay

• ‒ Disconnect fuel pump relay.

• ‒ → Connect the multimeter to contact 17 of relay socket and to earth to measure voltage.
• ‒ Specified value: approx. battery voltage

If specified value is not attained:

• ‒ Replace central electrics.

Checking actuation of fuel pump relay

• ‒ Switch ignition off.
• ‒ Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page 24-19.
• ‒ Jumper contacts 1 and 65 at test box with leads from adapter set V.A.G 1594A.
• ‒ Switch the ignition on.

• ‒ → Fuel pump relay (on central electrics in passenger's footwell on the left, position 4) must respond.

If the relay responds now, but not during final control diagnosis:

• ‒ Replace engine control unit => Page 24-32.

If the relay does not respond:

• ‒ Switch ignition off.
• ‒ Disconnect cable link.
• ‒ Disconnect fuel pump relay.

• ‒ → Connect multimeter as follows to measure voltage.

• ‒ Switch the ignition on.
• ‒ Specified value: approx. battery voltage

If specified value is not attained:

• ‒ Check the wiring connections.

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

If specified value is attained:

• ‒ Check for open circuit and short to positive or earth in the following wiring connections:

• ‒ Rectify any open/short circuit as necessary.

If no fault is found:

• ‒ Replace the fuel pump relay -J17.
• ‒ Reconnect engine control unit.

Checking voltage supply of fuel pump and components

• ‒ → Disconnect fuses S228, S232, S234 and S243 (positions 28, 32, 34 and 43) in fuse holder.
• ‒ Initiate final control diagnosis and actuate ACF solenoid valve -N80.
• ‒ To measure the voltage, connect multimeter to earth and to one of the contacts of the following fuses in the fuse holder.

If the specified values are not obtained:

• ‒ Repeat the test at the other contact of the fuse base.

If the specifications are still not attained:

• ‒ Check the wiring connections.

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

If no fault is found:

• ‒ Replace the fuel pump relay -J17.
• ‒ Reinsert the fuses.