Fuel Pump Activation (A4 & S4)
- Ensure battery voltage to be 12 volts or more. Check fuse No. 28 (15-amp). Fuse is located in instrument panel fuse box. Check fuel pump relay. Check that fuel filter is right one for vehicle, and not clogged. If no problem is found, go to next step. If problem is found, repair as necessary before continuing testing.
- Remove cover from instrument panel fuse box. Remove fuse No. 28. Connect remote control switch (VAG1348/3A) or equivalent, and appropriate adapter to right side terminal of fuse No. 28. Connect other end of remote control switch to battery voltage. Press remote control switch to ON position. Fuel pump should activate. Fuel pump should be able to be heard running (surrounding noise should be kept to a minimum, as fuel pump runs quietly). If fuel pump cannot be heard, go to next step.
- Remove rear seat bench by lifting up, and pulling forward. Remove fuel pump access cover. Disconnect fuel pump assembly 4-pin harness connector. Connect DVOM between fuel pump assembly harness connector terminals No. 1 and 4. See Fig 1
. Press remote control switch to ON position. If battery voltage does not exist, go to next step. If battery voltage exists, go to step 5
.
- Check for and repair, open or shorted circuits between fuel pump and instrument panel fuse box. See WIRING DIAGRAMS article.
- Remove fuel pump closing flange. See REMOVAL, OVERHAUL & INSTALLATION article. Check wiring and connections between flange and fuel pump. If problem is found, repair as necessary. After repair, retest fuel pump with remote control switch. If no problem with wiring is found, replace fuel pump. See REMOVAL, OVERHAUL & INSTALLATION article.
Courtesy of AUDI OF AMERICA, INC.