Alternator
The E46 330 uses a Bosch 120A alternator mounted to the front of the engine, driven by the serpentine belt.
Specifications
Section titled “Specifications”- Output: 120A (140A on some later models)
- Manufacturer: Bosch
- Voltage regulator: Internal, integrated
Failure Symptoms
Section titled “Failure Symptoms”- Battery light on dashboard
- Dim headlights
- Electrical accessories acting erratically
- Battery repeatedly dying
- Whining noise from front of engine (bearing failure)
Diagnosis
Section titled “Diagnosis”- Check output voltage at battery: should be 13.8-14.4V with engine running
- If voltage is below 13.5V or above 15.0V, the alternator or regulator is failing
Replacement Notes
Section titled “Replacement Notes”- The alternator is accessible from above the engine
- Remove the serpentine belt first
- Note the wiring connector orientation before disconnecting
- Remanufactured OE units are a cost-effective option