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

Note:

The power supply relay for Motronic -J271 supplies the ignition coils with output stages as well as the engine control unit on Pin 121 with voltage.

Test sequence

• ‒ → Remove engine cover-arrows-.

• ‒ → Unplug 4-pin connector -1- from one of the ignition coils -2-.

• ‒ → Connect multimeter as follows to measure voltage.

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

If specified value is not attained:

• ‒ Switch ignition off.

• ‒ → Disconnect the power supply relay -arrow- under left cover at the bulkhead.

Note:

To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.

• ‒ → Check for open circuit in the following wiring according to wiring diagram:

• ‒ Rectify open circuit, if necessary.

If the wiring is OK:

• ‒ Check the voltage supply of the power supply relay -J171 .
• ‒ Check the actuation of the power supply relay -J271 => Page 28-18.

Checking power supply

• ‒ Switch ignition off.
• ‒ → Disconnect the power supply relay -arrow- under left cover at the bulkhead.

Note:

To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.

• ‒ → Connect multimeter as follows to measure voltage.

• ‒ Specified value: approx. battery voltage

If specified value is not attained:

• ‒ Carry out the following tests (marked with dots):

• ● → Check fuse S10 (in fuse box, position 10).

• ● → Check fuse S134 (110 A) in main fuse box/battery.
• ● Check wiring from battery + (terminal 30) via fuse S134 and fuse 10 to power supply relay for Motronic -J271 (under left cover at bulkhead) for open circuit.

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

Checking actuation

• ‒ Switch ignition off.

• ‒ → Disconnect the power supply relay -arrow- under left cover at the bulkhead.

Note:

To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.

• ‒ → Connect multimeter as follows to measure voltage.

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

If specified value is not attained:

• ‒ 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.

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

• ‒ Rectify any open/short circuit as necessary.

If no fault is found:

• ‒ Replace the power supply relay -J271.