GM Service Manual Online
For 1990-2009 cars only

Disassembly Procedure

Tools Required

J 22912-O1 Bearing Remover

  1. Remove the generator from the vehicle. Refer to Generator Replacement .

  2. Object Number: 168892  Size: SH
  3. Scribe matchmarks (3) on the front (4) and rear housing (2) to ensure proper assembly.

  4. Object Number: 168896  Size: SH
  5. Remove 4 generator housing bolts from the front housing (2).

  6. Object Number: 168893  Size: SH
  7. Using a flat-bladed tool, gently pry off the front housing (7) (with the drive pulley and rotor) from the stator coil (1) and rear housing (2).
  8. Notice: To prevent damage to the rotor, place clean shop cloths between the rotor and the vise.

  9. Place the front housing and rotor (3) into a vise, facing the drive pulley up.
  10. Remove the drive pulley retaining nut.
  11. Remove the drive pulley washer and drive pulley from the rotor.
  12. Remove the front housing and rotor from the vise.
  13. Remove the rotor and spacer from the front housing.

  14. Object Number: 168898  Size: SH
  15. Remove the four screws (1, 3), the front bearing retainer and the front bearing from the front housing.

  16. Object Number: 168899  Size: SH
  17. Remove the rear bearing (1) from the rotor (2) using a J 22912-O1 and a press.

  18. Object Number: 168901  Size: SH
  19. Remove the battery terminal retaining nut (2) from the rear housing.
  20. Remove the stator leads from the rectifier using a soldering iron.

  21. Object Number: 168904  Size: SH
  22. Remove four retaining screws (2) and the stator (3) from the rear housing.
  23. Remove one nut and the rectifier from the rear housing.
  24. Remove the regulator and the brush holder from the rear housing.
  25. Remove the brush holder from the regulator.

  26. Object Number: 168900  Size: SH
  27. Remove the brushes from the regulator.
  28. 18.1. Remove the brush lead wire cover (4)
    18.2. Using a soldering iron, heat and disconnect the brush lead wires (2) from the regulator terminals (3).
    18.3. Remove the brushes and the brush springs from the regulator (1).

Measuring Procedure

Tools Required

    • J 39200 Digital Multimeter
    • J 26900-5 Vernier Caliper
  1. Inspect the rotor slip rings for roughness or scoring. If the slip rings are rough or scored, replace the rotor.

  2. Object Number: 168903  Size: SH
  3. Measure the resistance between the rotor slip rings (2) using a J 39200 . If the resistance is greater than 3.5 ohms, replace the rotor (1).

  4. Object Number: 168905  Size: SH
  5. Measure the resistance between the rotor slip rings (2) and the rotor (1) using the J 39200 . If the resistance is less than 5 ohms, replace the rotor.

  6. Object Number: 168906  Size: SH
  7. Measure the resistance between all stator leads (1) using the J 39200 . If the resistance is greater than 5 ohms for any measurement, replace the stator.

  8. Object Number: 168907  Size: SH
  9. Measure the resistance between all stator leads (1) and the stator core using the J 39200 . If the resistance is less than 5 ohms, replace the stator.

  10. Object Number: 168910  Size: SH
  11. Measure the length of each brush (1) using a J 26900-5 . If the brush length is less than the minimum, replace the brush.
  12. Standard Brush Length
    16 mm (0.63 in)

    Minimum Brush Length
    2 mm (0.08 in)


    Object Number: 168911  Size: SH
  13. Measure the resistance between the rectifier upper body (2) and each diode lead (1) using the J 39200 . Reverse the probes and measure the resistance again. If the resistance is not less than 5 ohms in one measurement and greater than 5 ohms in the other measurement, replace the rectifier.

  14. Object Number: 168913  Size: SH
  15. Measure the resistance between the rectifier lower body (2) and each diode lead (1) using the J 39200 . Reverse the probes and measure the resistance again. If the resistance is not less than 5 ohms in one measurement and greater than 5 ohms in the other measurement, replace the rectifier.

  16. Object Number: 168914  Size: SH
  17. Measure the resistance between both leads of each rectifier diode trio (1) using the J 39200 . Reverse the probes and measure the resistance again. If the resistance is not less than 5 ohms in one measurement and greater that 5 ohms in the other measurement, replace the rectifier.

  18. Object Number: 168916  Size: SH
  19. Measure the condenser (2) capacity using a digital capacitor meter. If the condenser capacity is not 0.5 microfarads, replace the rectifier.

Assembly Procedure


    Object Number: 168925  Size: SH
  1. Install the brushes (2) to the regulator (1).
  2. Install the brush springs and brushes to the regulator so that the label on each brush is 2 to 3 mm (0.008 to 0.012 in) from the rectifier.

  3. Object Number: 168900  Size: SH
  4. Solder the brush lead wires (2) to the regulator terminals (3).
  5. Install the brush lead wire cover (4).
  6. Install the brush holder to the regulator.
  7. Install the regulator and the brush holder to the rear housing
  8. Remove the hole plug from the rear housing.

  9. Object Number: 168927  Size: SH
  10. Support the brushes with a wire (2) inserted through the hole in the rear housing.
  11. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    Object Number: 168904  Size: SH
  12. Install the rectifier to the rear housing. Secure the rectifier with one nut.
  13. Tighten
    Tighten the generator rectifier nut to 33 N·m (24 lb ft).

  14. Install the stator (3) to the rear housing. Secure the stator with four retaining screws.
  15. Solder the stator leads to the rectifier.

  16. Object Number: 168901  Size: SH
  17. Install the battery terminal retaining nut (2) to the rear housing.
  18. Tighten
    Tighten the battery terminal retaining nut to 10 N·m (89 lb in).

  19. Install the rear bearing to the rotor.

  20. Object Number: 168898  Size: SH
  21. Install the front bearing and the front bearing retainer to the front housing. Secure the front bearing with four screws (1,3).

  22. Object Number: 168893  Size: SH
  23. Install the rotor with the spacer to the front housing.
  24. Notice: To prevent damage to the rotor, place clean shop cloths between the rotor and the vise.

  25. Place the front housing and rotor into a vise, facing the drive pulley end up.
  26. Install the drive pulley and the drive pulley washer to the rotor. Secure the drive pulley with a retaining nut.
  27. Tighten
    Tighten the drive pulley retaining nut to 65 N·m (48 lb in).

  28. Remove the front housing and the rotor from the vise.
  29. Using a heat gun, heat the rear housing to approximately 50 to 60°C (122 to 140°F).
  30. Install the front housing (4) (with the drive pulley and the rotor) to the stator coil (5) and the rear housing (6), aligning the generator housing matchmarks.

  31. Object Number: 168896  Size: SH
  32. Install the 4 front housing generator housing bolts (1,3).
  33. Tighten
    Tighten the generator housing bolts to 17 N·m (10 lb ft).

  34. Remove the brush support wire and install the hole plug into the rear housing.
  35. Make sure that the rotor rotates smoothly by turning the drive pulley.
  36. Install the generator to the vehicle. Refer to Generator Replacement .