Checking the ignition coil (Audi 100 C3)

The ignition coil fails very rarely. The coil is checked with an ohmmeter, measuring the resistance of the primary and secondary windings.

Execution order

1. Disconnect the wire from the negative terminal of the battery.

2. Disconnect the wires from the coil.

3. Inspect the coil. If the coil has cracks or the plug at the top of the coil has been pushed out, it needs to be replaced.

4. To check the resistance of the primary winding, connect an ohmmeter to terminals 6 and 4 (see Fig. Elements of a transistor ignition system). The resistance should be 0.5–0.8 Ohm.

5. To check the resistance of the secondary winding, connect an ohmmeter to terminals 4 and 5 (see Fig. Elements of a transistor ignition system). The resistance should be 2.4–3.5 kOhm.