Checking the installed generator (Audi A3 8L)

During normal driving, the charge control lamp should go out. Otherwise, the fault lies in the generator or voltage regulator. First, check the electrical connections of the generator. Check if the drive belt is tensioned correctly. Further testing can only be carried out with the generator removed, but all fuses should be checked first.

Checking the voltage regulator

1. Connect the voltmeter between the positive and negative terminals of the battery.

2. Start the engine. When starting, the voltage may drop to 8 V (at an outside temperature of +20°C).

3. Increase the engine speed to 3000 rpm. The voltage should be between 13.5 and 14.5 V. This indicates that the generator and regulator are working. Generator voltage (on-board voltage) must be higher than the battery voltage so that the battery is charged while driving.

4. Check the stability of the voltage regulator. To do this, turn on the high beam and repeat the measurements at 3,000 rpm. The measured voltage should not be greater than 0.4 V of the previously measured value.

5. If the voltage does not correspond to the required values, the cause of the malfunction may be worn generator brushes, weak brush springs, a faulty voltage regulator, a faulty diode, a broken stator winding, or defective rotor slip rings.