12 31 009 Checking alternator and regulator switch
Test Requirements:
- Correct connections on charged battery.
- Correct connections on alternator and starter motor.
- Good ground connection between engine and body.
- Tightened drive belt.
Connect DIS Tester.
- Measurement.
- Checking alternator.
If charge indicator lamp is permanently lit:
Remove voltage regulator and check carbon brushes, replace if necessary.
Replace alternator regulator switch.
If charge indicator lamp goes out while engine is running:
Check control voltage.
Regulator switch must be replaced if control voltage is not achieved.
Replace alternator regulator switch.
From E46/E39 With Multifunction Regulator.
Recognizable by plug connection on regulator.
Connect DIS Tester.
- Function selection.
- Complete vehicle.
- Drive.
- Voltage and current regulation.
- Voltage and current generation.
- Work through test modules.
Oscillogram For A Fault-Free Alternator:
Oscillogram For A Faulty Alternator:
One phase interrupted.
Repair/exchange alternator.
Interturn fault.
Repair/exchange alternator.
Open circuit in negative diode.
Repair/exchange alternator.
Short circuit in positive diode.
Repair/exchange alternator.
Open circuit in positive diode.
Repair/exchange alternator.
Open circuit in exciter diode.
Repair/exchange alternator.