Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ V.A.G 1526 A
• ◆ V.A.G 1527 B
• ◆ V.A.G 1594 A
• ◆ V.A.G 1598/31

Test sequence

Note:

The ignition coil and the output stage is combined in a common component.

• ‒ → Remove engine cover -arrows-.

Identify an inoperative or misfiring cylinder as follows:

• ‒ Check misfire detection .

If misfires are detected:

• ‒ Continue checking the indicated cylinder => "If the defective cylinder has been detected".

If no misfires were detected:

• ‒ Disconnect connectors from the injectors in sequence with the engine running, and observe how the engine runs.

or

• ‒ Compare the spark plugs of all cylinders with each other and check for soot on the electrodes.

If the defective cylinder has been identified:

• ‒ Replace the spark plug of the defective cylinder with one from another cylinder.

If the fault moves with the spark plug:

• ‒ Renew the spark plug.

If the fault remains in the same cylinder:

• ‒ Interchange the ignition coil from the defective cylinder with one from another cylinder.

If the fault moves with the ignition coil:

• ‒ Replace the ignition coil.

Test earth connection

• ‒ → Unplug 4-pin connector -1- from ignition coil -2-.

• ‒ → Connect voltage tester V.A.G 1527 B as follows:

• ‒ The LED should light up.

If the LED does not light up:

• ‒ Check the wiring connections.

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

If the LED lights up:

• ‒ Check the power supply.

Checking power supply

Test requirements:

• ● Fuses for engine electronics OK

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

• ‒ → Connect multimeter as follows to measure voltage:

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

If specified value is attained:

• ‒ Check actuation of output stages => Page 28-10.

If specified value is not attained:

• ‒ → 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-.

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

• ● → Check the wiring of 3-pin relay carrier, position 2, contact 6 to connector of ignition coil contact 1.
• ● Check power supply relay for Motronic -J271 => Page 28-13.

Checking actuation of power output stages

• ‒ Unplug connectors from all injectors.

Note:

It is important to ensure that no fuel is injected during the test, as this would damage the catalytic converter. Therefore, the connectors on the injectors must be unplugged.

• ‒ → Unplug 4-pin connector -1- from ignition coil -2-.

• ‒ → Connect voltage tester V.A.G 1527 B to contacts 2 and 3 of the connector.
• ‒ Operate starter briefly.
• ‒ The diode test lamp should flash (very brief flash).

If specified values are not attained:

• ‒ 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 connections:

• ‒ Rectify any open/short circuit as necessary.

If no wiring fault is detected:

• ‒ Replace the common component ignition coil with output stage.