Battery charging system malfunctions (Audi 100 C4)

Below are some malfunctions, their possible causes and solutions, which can help in diagnosis.

The battery charge indicator lamp does not light when the ignition is turned on. The battery is discharged. Use an additional battery or start the engine while towing the vehicle.

The light bulb burned out.

The wire on the battery terminal is loose or oxidized. Check the connection. In extreme cases, rinse with warm water, but it is better to use a special cleaning agent

The circuit between the ignition switch, the control lamp and the generator is broken. It is recommended to have everything checked in a workshop.

The ground wire between the generator and the engine is broken or loose. Check it.

Brushes, voltage regulator or generator faulty. Replace brushes and regulator as described above. Have the generator repaired or replaced.

The indicator light comes on or flashes when the engine is running

If all wires are connected and not damaged, the V-belt may be loose or the belt tensioner may be faulty. Check them. Other causes may be worn alternator brushes and faulty voltage regulator/alternator.