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 power.

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.

• ‒ → Remove rubber seal from plenum chamber cover in direction of arrow.
• ‒ Remove plenum chamber cover -1- from the front.

• ‒ → Remove cover for electronics box (plenum chamber) -arrows-.

• ‒ → Pull off power supply relay -3-.

• ‒ → 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 28-19.

Checking power supply

• ‒ → 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 the wiring between central electrics and power supply relay for open circuit.

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

If no wiring fault is detected:

• ‒ Replace central electric's.

Checking actuation

• ‒ → 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 the V.A.G 1598/31 test box to wiring harness leading to engine control unit; the engine control unit should not be connected => 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.