GM Service Manual Online
For 1990-2009 cars only

Disassembly Procedure


    Object Number: 1776820  Size: SH
  1. Remove the generator. Refer to Generator Replacement.
  2. Mark a match line that cannot easily be removed on the end frame to make assembly easier.
  3. Pry off the plastic cover to expose the stator connections.

  4. Object Number: 1776822  Size: SH

    Note: If the stator connections are not welded, melt the lead. Avoid excessive heating, as it can damage the diodes in the rectifier bridge.

  5. Remove the stator connections from the rectifier bridge terminals by cutting the wires.

  6. Object Number: 1776825  Size: SH
  7. Pry off the baffle.
  8. Remove the rectifier/regulator/brush holder assembly screws.
  9. Note: If the brush can be reused, reassemble the brush to the holder with the retaining pin, after cleaning the brush with a soft, clean cloth.

  10. Remove the brush holder assembly and the regulator.

  11. Object Number: 1776827  Size: SH
  12. Test the rectifier bridge by connecting the ohmmeter terminals to the bridge and the heat sink.

  13. Object Number: 1776830  Size: SH
  14. Retest by connecting the ohmmeter terminals in reverse.

  15. Object Number: 1776827  Size: SH
  16. Replace the rectifier bridge, if each reading is the same.
  17. Test the remaining two diodes after the above procedure.
  18. Note: Some kinds of digital ohmmeters are not suited for the test of the bridge diode. In this case, consult the manufacturer regarding the test capacity.

  19. Test the diodes by connecting the ohmmeter terminals to the bridge terminal and the base plate. If the reading is the same, the rectifier bridge should be replaced.

  20. Object Number: 1776831  Size: SH
  21. Remove the generator through-bolts.

  22. Object Number: 1776833  Size: SH

    Note: The fastening torque of this nut is 81 N·m (60 lb ft) and may not normally be unfastened using hand strength.

  23. Move to the drive end of the generator and remove the drive end bearing nut.
  24. Remove the pulley and the collars.

  25. Object Number: 1776837  Size: SH
  26. Test the rotor for an open circuit using the ohmmeter with the drive end frame assembled. The reading should be sufficiently high, or the rotor must be replaced.

  27. Object Number: 1776838  Size: SH
  28. Test the rotor for open and short circuits. The reading should be 1.7-2.3, or the rotor should be replaced.

  29. Object Number: 1776840  Size: SH
  30. Remove the drive end frame from the shaft.
  31. For vehicles with an internal generator fan, remove the drive end frame and the fan.

  32. Object Number: 1776841  Size: SH
  33. Remove the rotor assembly.

  34. Object Number: 1776847  Size: SH
  35. Remove the stator.

  36. Object Number: 1776853  Size: SH
  37. Test the stator for an open circuit using the ohmmeter.

  38. Object Number: 1776856  Size: SH
  39. Remove the ring in the slip ring end frame.

Assembly Procedure


    Object Number: 1776831  Size: SH
  1. Install the new ring in the slip ring end frame.
  2. Install the stator.
  3. Position the rotor assembly shaft with the drive end frame in the slip ring end assembly until the gap between the outer lace and the end frame casting is 1.9 mm (0.075 in).
  4. Caution: Refer to Fastener Caution in the Preface section.

  5. Install the generator through-bolts and tighten to 10 N·m (89 lb in).

  6. Object Number: 1776833  Size: SH
  7. Position the fan, the collars, and the pulley on the rotor shaft and secure with the nut and tighten to 81 N·m (60 lb ft).
  8. Install the generator. Refer to Generator Replacement.

  9. Object Number: 1776825  Size: SH
  10. Weld the brush holder terminal to the regulator terminal, if removed
  11. Fix the brush holder with the retainer pin, and weld the regulator/brush holder assembled terminal to the rectifier terminal.
  12. Apply silicone grease between the bridge and the end frame for radiation purposes.
  13. Fasten the screws holding the rectifier regulator/brush holder assembly to the end frame.
  14. Punch the new baffle with the pin into the brush.

  15. Object Number: 1776822  Size: SH

    Note: Take care to prevent damage to the vehicle by protecting the diode in the rectifier bridge from excessive heat while welding.

  16. Weld the connectors of the rectifier bridge.