Audi Workshop Service and Repair Manuals

Checking ignition coils with output stages Special tools and workshop equipment required t  Portable multimeter -V.A.G 1526C- t  Voltage tester -V.A.G 1527B- t  Adapter set -V.A.G 1594C- t  121-pin adapter cable -V.A.G 1598/31-

Test sequence   Note The ignition coil and the output stage are combined in a joint component.

–  Remove the engine cover -arrows-. The procedure for identifying an inoperative or misfiring cylinder is as follows: –  Check misfiring detection → Chapter and → Chapter. If misfiring has been detected: –  Continue with testing at cylinder indicated ⇒ “When defective cylinder has been identified”. If no misfiring has been detected: –  With the engine running, consecutively unplug the connectors from the injectors and observe engine operation. or –  Compare the spark plugs of all cylinders, paying attention to soot deposits on the electrodes. When defective cylinder has been identified: –  Interchange the spark plug of the defective cylinder with that of a different cylinder. If the fault now occurs at the other cylinder: –  Replace the spark plug. If the fault remains in the same cylinder: –  Interchange the ignition coil of the defective cylinder with that of a different cylinder. If the fault now occurs at the other cylinder: –  Replace the ignition coil. Checking earth connections

–  Unplug the 4-pin connector -1- at the ignition coil -2-.

–  Connect up the voltage tester -V.A.G 1527B- as follows:

Connector Contact	Measure to
2	Battery positive
4	Battery positive

t  The LED must light If the LED does not light: –  Check the wiring. → Current flow diagrams, Electrical fault finding and Fitting locations If the LED lights up: –  Check voltage supply. Checking voltage supply of output stages   Note Engine electronics fuses OK → Current flow diagrams, Electrical fault finding and Fitting locations

–  Connect up the multimeter (voltage measuring range) as follows:

Connector Contact	Measure to
1	Engine earth

–  Switch on ignition. t  Specification: approx. battery voltage If the reading matches the specification: –  Check activation of output stages. If the reading does not match the specification:

–  Detach the current supply relay -1- beneath the cover on the left at the bulkhead. –  Perform the following checks marked with a dot:

l  Check the wiring from the relay carrier beneath the cover on the left at the bulkhead, contact 2 to the connector at the ignition coil, contact 1. l  Check the Motronic current supply relay -J271- → Chapter. If the specification is obtained: –  Check activation. Checking actuation of output stages –  Unplug the connectors at all injectors.   Note It is important to ensure that no fuel is injected during the check as this would damage the catalytic converter. The connectors must therefore be unplugged from the injectors.

–  Unplug the 4-pin connector -1- at the ignition coil -2-.

–  Connect up the voltage tester -V.A.G 1527B- to contacts 2 and 3 of the connector. –  Briefly operate the starter. t  The LED should flash (short signal) If the readings do not match the specifications: –  Connect the test box -V.A.G 1598/31- to the wiring harness to the engine control unit, but do not connect the actual engine control unit → Chapter.

–  Check for open circuit and short to earth or positive in the following wiring:

Connector Contact	Test box -V.A.G 1598/31- Socket
3 (cyl. 1)	102
3 (cyl. 2)	95
3 (cyl. 3)	103
3 (cyl. 4)	94

–  Eliminate open circuit in wiring/short circuit if necessary. If no fault is found in the wiring: –  Renew ignition coil with output stage (combined as a single component).