GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Blazer - 4WD - RHD 🢒 Steering 🢒 Steering Wheel and Column 🢒 Lock Module Replacement

Removal Procedure

    Caution: Refer to SIR Caution in the Preface section.


    Object Number: 421408 Size: SH
  1. Disable the SIR system. Refer to SIR Disabling and Enabling in SIR.
  2. Remove the turn signal cancel cam and upper bearing inner race. Refer to Turn Signal Cancel Cam and Upper Bearing Thrust Washer .
  3. Remove the windshield wiper and washer switch assembly only. Refer to Windshield Wiper and Washer Switch Replacement in Wipers/Washers System.
  4. Remove the turn signal and multifunction switch assembly only. Refer to Turn Signal Multifunction Switch Replacement .

    5. Important: When removing the horn contact, the horn contact spring may become a projectile. Remove slowly.

  5. Remove the horn contact (2) from the signal switch housing assembly (1) in the following manner:
    6. 5.1. Turn the horn contact plunger to release it from the signal switch housing assembly (1).
    5.2. Remove the horn contact (2) and the spring.

    Object Number: 421407 Size: SH
  6. Remove the 2 washer head screws (1) from the signal switch housing assembly (2).
  7. Slide the signal switch housing assembly (2) off of the steering shaft assembly.

    8. Object Number: 421401 Size: SH
  8. Disconnect the connector (3) from the ignition switch assembly (2).
  9. Remove the 2 tapping screws (1) from the ignition switch assembly (2).
  10. Remove the ignition switch assembly (2) from the lock cylinder housing assembly.

    11. Object Number: 421404 Size: SH
  11. Remove the 2 tapping screws (2) from the A/T shift lock control.
  12. Remove the A/T shift lock control (1) from the lock cylinder housing assembly.

    13. Object Number: 421727 Size: SH
  13. Use a drill in order to drill the 2 shear bolts (1) through the steering column tilt head assembly.
  14. Remove the lock cylinder housing assembly (3) from the steering column tilt head assembly.
  15. Use the locking pliers to remove the shear bolts (1) form the lock cylinder housing assembly (3).
  16. Remove the 2 shear bolt washers (2).
  17. Discard the shear bolts (1).

Installation Procedure

    Object Number: 421727 Size: SH
  1. Install the 2 shear bolt washers (2) onto the lock cylinder housing assembly (3).
  2. Install the lock cylinder housing assembly (3) onto the steering column tilt head assembly.
  3. Install the 2 shear bolts (1) through the steering column tilt head assembly and into the lock cylinder housing assembly (3).

    4. The shear bolts (1) will snap off when tightened.


    Object Number: 421402 Size: SH
  4. Install the A/T shift lock control (2) to the lock cylinder housing assembly.

    5. 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.

  5. Install the 2 tapping screws (1) into the A/T shift lock control (2).

    6. Tighten
    Tighten the screws to 1.5 N·m (13 lb in).


    Object Number: 421401 Size: SH
  6. Install the ignition switch assembly (2) to the lock cylinder housing assembly.
  7. Install the 2 tapping screws (1) into the ignition switch assembly (2).

    8. Tighten
    Tighten the screws to 1.5 N·m (13 lb in).

    Caution: Improper routing of the wire harness assembly may damage the inflatable restraint steering wheel module coil. This may result in a malfunction of the coil, which may cause personal injury.

  8. Connect the connector (3) to the ignition switch assembly (2).

    9. Object Number: 421407 Size: SH
  9. Slide the signal switch housing assembly (2) onto the steering shaft assembly.
  10. Install the 2 washer head screws (1) into the signal switch housing assembly (2).

    11. Tighten
    Tighten the screws to 3.5 N·m (31 lb in).


    Object Number: 421408 Size: SH
  11. Insert the horn contact spring and the horn contact (2) into the signal switch housing assembly (1).
  12. Insert the horn contact plunger into the signal switch housing assembly (1) and turn to lock in place.
  13. Install the turn signal and multifunction switch assembly only. Refer to Turn Signal Multifunction Switch Replacement .
  14. Install the windshield wiper and washer switch assembly only. Refer to Windshield Wiper and Washer Switch Replacement in Wipers/Washers System.
  15. Install the turn signal and multifunction switch assembly. Refer to Turn Signal Cancel Cam and Upper Bearing Thrust Washer .
  16. Enable the SIR system. Refer to SIR Disabling and Enabling in SIR.