GM Service Manual Online
For 1990-2009 cars only

Key Identification and Usage


Object Number: 793164  Size: SH

The keys are double sided and reversible. The master key and valet key contain transponders that are read by the theft deterrent system when the keys are used in the ignition. The keys have 10 cut positions (1) with five different depths (2).

The keys that may be furnished with the vehicle consist of the following:

    • The master key, which contains a transponder (3). This key will operate all of the locks on the vehicle.
    • The valet key, which contains a transponder (3). This key will operate the front door locks and the ignition lock only.
    • The emergency key, which does not contain a transponder. This key will operate the door locks, rear compartment lock and the I/P storage compartment lock only. This key is intended for emergency use only.

Cutting Keys


Object Number: 793164  Size: SH

The key code can be obtained from the four digit number on the key tag that accompanies the original master and valet keys. The five digit key code cross references to the cut and tumbler sequence. The keys have 10 key cut positions (1) and five key cut depths (2). Key cut positions are numbered 1-10, counting from the head of the key to the tip. The key cut depths are 1-5, cut depth number 1 is the deepest cut. The key transponder (3) in the master and valet key must be programmed to the vehicle. Refer to Programming Theft Deterrent System Components in Theft Deterrent.

  1. Cut a blank key to the proper depth and sequence of each of the tumbler positions.
  2. Inspect the mechanical operation of the key in the lock cylinders in the doors, the ignition switch, the rear compartment lid and any storage compartments:
  3. With each side of the key pointing up inside the lock, inspect the operation of the lock in both directions.

    • Turn the key both directions in each lock cylinder.
    • Turn the key with each side of the key pointing upward in each lock cylinder.
  4. If replacing a master or valet key, program the key transponder to the vehicle. Refer to Programming Theft Deterrent System Components in Theft Deterrent.

Lock Cylinder Tumbler Operation

Each of the four cut depths on the key has corresponding tumblers, sometimes referred to as plates or wafers. The tumbler depth number is stamped on the tumblers for identification. The I/P storage compartment and the rear compartment lid release lock cylinder also require a retainer tumbler. The retainer tumbler is not moved by the key, its function is to retain the I/P storage compartment lock cylinder in the lock assembly.

Assembling and Coding Ignition Lock Cylinder

The ignition lock cylinder uses nine of the ten cut positions, 1 through 9. The tumbler positions are staggered from side to side, five on one side and four on the other.


    Object Number: 550188  Size: SH

    Important: The ignition lock cylinder tumblers (2) are not self retaining and must be held in place if the key is not fully inserted into the lock cylinder, or the tumbler retainer (1) is properly staked into the cylinder.

  1. Hold the cylinder (5) so that the side with five tumbler spring wells is facing up.
  2. Insert tumbler springs (3) into the five spring wells.
  3. The first tumbler to be loaded will be the 1st key cut position (the first number in the key code). Install the first tumbler (2) in the slot nearest the front of the lock cylinder, this is the side into which the key would be inserted. It may be necessary to move the sidebar (4) out slightly to fully install the tumbler (2).
  4. Install the four remaining tumblers on this side of the lock cylinder, key cut positions 3, 5, 7 and 9.
  5. Inspect for correct loading of the tumblers (2) by inserting the key into cylinder (5). The sidebar (4) should be flush with the outside diameter of the cylinder (5).
  6. Turn the cylinder (5) so that the side with the four tumbler spring wells is facing up. Remove the key.
  7. Insert the tumbler springs (3) into the four spring wells.
  8. Install the tumbler (2) for the key cut position 2 into the slot nearest to the front of the lock cylinder.
  9. Install the three remaining tumblers, key cut positions 4, 6 and 8, on this side of the lock cylinder.
  10. Inspect for correct loading of the tumblers (2) by inserting the key into cylinder (5). The sidebar (4) should be flush with the outside diameter of the cylinder (5).
  11. Lightly lubricate the tumbler (2) surfaces using the provided lubrication.

  12. Object Number: 550194  Size: SH
  13. With the key inserted into the housing, install and carefully stake one tumbler retainer (1) into the recessed area (2) on the cylinder.
  14. Turn over the cylinder and carefully stake the other tumbler retainer (1) into the recessed area (2) on the cylinder.

Assembling and Coding Door Lock Cylinder

The front side door lock cylinder only uses seven of the ten cut positions, 4-10. The tumbler positions are staggered from side to side (4 on one side and 3 on the other). The left and right door lock cylinders are identical. The lock pawl determines which side of the vehicle the lock cylinder is on.


    Object Number: 550196  Size: SH

    Important: The front side door lock cylinder tumblers (10) are not self retaining and must be held in place if the key is not fully inserted into the lock cylinder, or until the cylinder  (9) is assembled into the case assembly (11).

  1. Hold the cylinder (9) so that the side with four tumbler spring wells faces up.
  2. Insert tumbler springs (5) into the four spring wells.
  3. Install the tumbler for key cut position 4 in the slot nearest to the front of the lock cylinder.
  4. Install the three remaining tumblers, key cut positions 6, 8 and 10, on this side of the lock cylinder.
  5. Inspect for correct loading of the tumblers (10) by inserting the key into cylinder (9). All of the tumblers should be flush with the outside diameter of the lock cylinder.
  6. Turn the cylinder (9) so that the side with three tumbler spring wells faces up.
  7. Insert the tumbler springs (5) into the three spring wells.
  8. Install the tumbler for key cut position 5 into the slot nearest the front of the lock cylinder.
  9. Install the two remaining tumblers for key cut positions 7 and 9 on this side of the lock cylinder.
  10. Inspect for correct loading of the tumblers (10) by inserting the key into cylinder (9). All of the tumblers should be flush with the outside diameter of the lock cylinder.
  11. Lightly lubricate the tumbler (10) surfaces using the provided lubrication.
  12. Hold the case assembly (11) with the pre-staked detent spring retainer facing downward.
  13. Caution: Wear safety glasses in order to avoid eye damage.

  14. Insert one detent spring (3) and one detent ball (4) into the hole located to the rear and inside of the case assembly (11).
  15. Insert the key into the lock cylinder.
  16. Ensure the detent spring (3) and ball (4) are held in place until the cylinder is fully installed. Install the cylinder into the case assembly (11). The detent ball (4) will line up with the V-shaped groove on the rear of the cylinder.
  17. Carefully remove the key, keeping the lock cylinder (9) inserted into the case assembly (11).
  18. Insert one shutter spring (8) into each hole located on the front of the cylinder (9).
  19. Install the shutter assembly (7) into the recessed area in the front of the cylinder (9). Ensure the ends of the pin on the shutter assembly (7) are positioned in the pin cavities located on the front face of the cylinder (9).
  20. Install the lock cylinder cap (6) by aligning the two notches in the cap with the drain hole located on the bottom of the case assembly (11) and the corresponding feature on the top of the case assembly (11).
  21. Press the cap into place with light hand pressure.

  22. Install the appropriate lever (2).
  23. Install the retaining ring (12).
  24. Snap the appropriate rod retainer (1) into the hole in the lever (2).

Assembling and Coding Rear Compartment Lid Lock

The rear compartment lock cylinder only uses seven of the ten cut positions, 4-10. The tumbler positions alternate in adjacent locations from side to side with four on one side and three on the other.


    Object Number: 550197  Size: SH

    Important: The rear compartment lid lock cylinder tumblers (7) are not self retaining and must be held in place if the key is not fully inserted into the lock cylinder, or until the cylinder  (6) is assembled into the case assembly (1).

  1. Hold the cylinder (6) so that the side with four tumbler spring wells faces up.
  2. Insert the tumbler springs (2) into the four spring wells.
  3. Insert the tumbler (7) for key cut position 3 into the slot nearest to the front of the lock cylinder (6).
  4. Install the three remaining tumblers, key cut positions 6, 8 and 10, on this side of the lock cylinder.
  5. Inspect for correct loading of the tumblers (7) by inserting the key into cylinder (6). All of the tumblers should be flush with the outside diameter of the lock cylinder (6).
  6. Turn the cylinder (6) so that the side with three tumbler spring wells faces up.
  7. Insert the tumbler springs (7) into the three spring wells.
  8. Install the tumbler (7) for key cut position 5 into the slot nearest to the front of the lock cylinder.
  9. Install the two remaining tumblers, key cut positions 7 and 9, on this side of the lock cylinder.
  10. Inspect for the correct loading of the tumblers (7) by inserting the key into the cylinder (6). All of the tumblers should be flush with the outside diameter of the lock cylinder (6).
  11. Lightly lubricate the tumbler (7) surfaces using the provided lubrication.
  12. Install the lock cylinder (6) into case assembly (1).
  13. Carefully remove the key, keeping the lock cylinder (6) inserted into the case assembly (1).
  14. Insert one shutter spring (5) into each hole located on the front of the cylinder (6).
  15. Install the shutter assembly (4) into the recessed area in the front of the cylinder (6). Ensure the ends of the pin on the shutter assembly (4) are positioned in the pin cavities located on the front face of the cylinder (6).
  16. Install the lock cylinder cap (3) by aligning the two notches in the cap with the drain hole located on the bottom of the case assembly (1) and the corresponding feature on the top of the case assembly (1).
  17. Press the cap into place with light hand pressure.

Assembling and Coding Rear Compartment Lid Release Lock Cylinder

The rear compartment lid release lock cylinder uses four of the ten cut positions 7-10 . A retainer tumbler is used in the rear compartment lid release lock cylinder to retain the lock cylinder in the latch assembly. This retainer tumbler is not moved by the key. The retainer tumbler occupies the slot closest to the head of the rear compartment lid release lock cylinder and should come already installed in the cylinder.


    Object Number: 550199  Size: SH
  1. Hold the cylinder (3) so that the side with four tumbler spring wells is facing up.
  2. Insert tumbler springs (2) into the four spring wells.
  3. Install the tumbler (1) for key cut position 7 into the slot nearest to the front of the lock cylinder.
  4. Install the three remaining tumblers, key cut positions 8, 9 and 10, into the cylinder.
  5. Snap the tumblers into place with light hand pressure.
  6. Inspect for the correct loading of the tumblers (1) by inserting the key into cylinder (3). All of the tumblers should be flush with the lock cylinder.

Assembling and Coding I/P Storage Compartment Lock Cylinder

The I/P storage compartment lock only uses four of the ten cut positions 7-10 . A retainer tumbler is used in the I/P storage compartment lock to retain the lock cylinder in the latch assembly. This retainer tumbler is not moved by the key. The retainer tumbler occupies the slot closest to the head of the I/P storage compartment lock cylinder and should come already installed in the cylinder.


    Object Number: 550198  Size: SH
  1. Hold the cylinder (3) so that the side with four tumbler spring wells is facing up.
  2. Insert tumbler springs (2) into the four spring wells.
  3. Install the tumbler (1) for key cut position 7 into the slot nearest to the front of the lock cylinder.
  4. Install the three remaining tumblers, key cut positions 8, 9 and 10, into the cylinder.
  5. Snap the tumblers into place with light hand pressure.
  6. Inspect for the correct loading of the tumblers (1) by inserting the key into cylinder (3). All of the tumblers should be flush with the lock cylinder.