I have a volt meter gadget plugged into the cigarette lighter socket. It used to read at 14.3 volts when the car is running. Suddenly it dropped to 11.2 volts without any accessories or lights on. I decided to disconnect the negative cable from the battery and the engine stopped running. Is it the alternator that's bad or just the carbon brush?
There could be a number of reasons for the failure -
- Snapped belt.
- Disconnected cables to the alternator
- Broken fuseable link in the fusebox
- Faulty rectifier in the alternator
- Worn brushes in the alternator
- Broken coil in the alternator
- Faulty regulator in the alternator
After checking the cables and belt, you would need to dismantle the alternator to diagnose further.