GM Service Manual Online
For 1990-2009 cars only

Two Speed Rear Axle Shift Motor Replacement HPZ

Removal Procedure

  1. Apply the parking brake.
  2. Block the wheels.
  3. Shift the two-speed rear axle shift switch to the LOW range.

  4. Object Number: 199043  Size: SH
  5. Remove the two-speed rear axle wiring harness clip nut (1).
  6. Remove the two-speed rear axle wiring harness clip (2) from the stud.

  7. Object Number: 199122  Size: SH
  8. Disconnect the two-speed rear axle wiring harness connector.

  9. Object Number: 199050  Size: SH
  10. Remove the two-speed rear axle shift motor nuts (1) and the washers (2).
  11. Remove the two-speed rear axle shift motor (6).
  12. Remove the two-speed rear axle spring from the two speed rear axle shift fork (4).
  13. Remove the two-speed rear axle shift fork seal (5) from the differential carrier housing (3).

Installation Procedure


    Object Number: 199050  Size: SH
  1. Install the two-speed rear axle shift fork seal (5) onto the differential carrier housing (3).
  2. Install the two-speed rear axle shift fork spring onto the shift fork (4).

  3. Object Number: 199057  Size: SH
  4. Apply a thin coat of rear axle lubricant to the shift fork and the two-speed rear axle shift motor lever. Refer to Fluid and Lubricant Recommendations in General Information.

  5. Object Number: 199050  Size: SH

    Important: Ensure that the two-speed rear axle shift motor lever engages with the two-speed rear axle shift fork (4).

  6. Install the two-speed rear axle shift motor (6).
  7. 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.

  8. Install the two-speed rear axle shift motor washers (2) and the nuts (1).
  9. Tighten
    Tighten the nuts (1) to 74 N·m (55 lb ft).


    Object Number: 199122  Size: SH
  10. Connect the two-speed rear axle wiring harness connector.

  11. Object Number: 199043  Size: SH
  12. Install the two-speed rear axle wiring harness clip (2) onto the stud.
  13. Install the two-speed rear axle wiring harness clip nut (1).
  14. Tighten
    Tighten the nut (1) to 1.9 N·m (17 lb in).

  15. Turn the ignition switch to the ON position.
  16. Verify proper operation of the two-speed rear axle.
  17. Remove the wheel blocks.