Component Tests and General Diagnostics

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, refer to operating instructions.
Select "Measurement".
Select "Check alternator".







If the charge indicator lamp is permanently lit:
Remove voltage regulator and check carbon brushes, replace if necessary.
Replace regulator switch for alternator.


NOTE: Minimum length of carbon brushes "A" = 5 mm.







If charge indicator lamp goes out while engine is running:
Check control voltage,

Regulator E36:

If control voltage is not achieved, replace regulator switch.
Replace regulator switch on alternator.







Oscillograph of a fault-free alternator.







One phase interrupted.
Repair/exchange alternator.







Coil connection.
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.