Component Tests and General Diagnostics

CHECKING ALTERNATOR AND VOLTAGE REGULATOR

Testing Requirements:





- Correct connections on charged battery
- Correct connections on alternator and starter
- Good ground connection between engine and body.
- Tight drive belt

Indicator Lamp On Continuously:





- Remove voltage regulator and check carbon brushes, replacing if necessary - 12 31 200. Distance *'V" for new condition = approx. 12 mm (0.472").

Installation Note:





- Check slip rings for wear, fine grinding and polishing if necessary.

- Connect BMW service test unit. Start engine and compare test values with nominal values





- If the battery charge indicator lamp goes out while engine is running and the regulating voltage* is not reached - harmonic wave ratio and oscillograph okay (as shown) - the voltage regulator has to be replaced, see 1232000.
- Repeat test.





- If the specified charging current 5 not reached remove and disassemble alternator, and inspect components.





Oscillographs of Defective Alternator:
- Defective power or exciter diode.





- Shorted turn of stator coil.





- Break in one exciter diode.