GM Service Manual Online
For 1990-2009 cars only

Ignition Lock Cylinder

The ignition lock cylinder uses only 7 of the 10 cut positions, 2 through 8. The ignition cylinder tumblers (3) are located on alternate sides of the cylinder (1). They are snap-in and self-retaining. It follows the key code with the first tumbler being the first depth of the key code, closest to the head of the key.


    Object Number: 1978298  Size: SH
  1. Hold the ignition cylinder assembly (1) so the side with the tumbler spring pocket located closest to the head of the cylinder is facing up.
  2. Insert the tumbler spring (2) into each of the 4 spring pockets of the cylinder assembly.
  3. The first tumbler (3) to be loaded will be the second key cut position, which is the second number in the key code. Install the first tumbler in the slot over the spring. Install the remaining tumblers for cuts 4, 6, and 8 following the key code and same process, pressing the tumblers in place until they are secure.
  4. Rotate the cylinder assembly. Insert the tumbler spring into each of the spring pockets of the cylinder assembly.
  5. The first tumbler to be loaded will be the third key cut position, the third number in the key code. Install the first tumbler in the slot over the spring. Install the remaining tumblers for cuts 5 and 7 following the key code and same process, pressing the tumblers in place until they are secure.
  6. Inspect for correct loading of the tumblers by inserting the key into the cylinder. All tumblers should drop flush with the lock cylinder body diameter.
  7. Lightly lubricate the outside surface in the tumbler area of the lock body and down the key slot using the provided grease. Insert and extract the key 5 times to lubricate the keyway.
  8. With the key in the cylinder assembly, insert the actuator (4) in the actuator pocket and hold. Rotate the cylinder assembly and insert the retainer spring (6) in the retainer slot located in the cylinder assembly. Insert the retainer (7) lining it up in the slot over the spring. Depress the retainer and hold.
  9. Insert the cylinder into the sleeve (5) as shown in the print. Make sure the actuator stays located properly in the cylinder.
  10. When the key is removed, the lock should stay together.
  11. Insert the key and function the lock 3 times to distribute the grease inside the sleeve.
  12. Verify the key position for inserting the lock into the column.

Door Lock Cylinder

The door lock cylinder only uses 7 of the 10 cut positions, 4 through 10. The tumbler positions are staggered from side to side, 4 on one side and 3 on the other are self-retaining. The left and right door lock cylinders are identical. The lever assembly determines which side of the vehicle the lock cylinder is for. After removing the current lock, record which lever is used and the orientation of the rod clip.


    Object Number: 1978300  Size: SH
  1. Rotate the cylinder (1) so the side with the 4 tumblers spring wells faces up.
  2. Insert the tumblers springs (2) into the 4 spring wells.
  3. Install the tumbler (3) for key cut position 4 in the slot closest to the cylinder head. Install the remaining tumblers, key cut positions 6, 8, 10, following the key code and same process. Press tumblers in place until they are secure.
  4. Check the correct loading of the tumblers by inserting the key into the cylinder. All tumblers should be flush with the lock cylinder body.
  5. Turn the cylinder so the side with the 3 tumblers spring wells faces up.
  6. Insert the tumbler springs into the 3 spring wells.
  7. The first tumbler closest to the front of the lock cylinder to be loaded will be the fifth key cut position. Install the remaining tumblers for the key cut positions 7 and 9. Press tumblers in place until they are secure.
  8. Check the correct loading of the tumblers by inserting the key into cylinder. All of the tumblers should be flush with the lock cylinder body.
  9. Apply lubricant to cylinder body and tumbler surfaces along with a small amount in head of cylinder using the supplied grease.
  10. Install 2 springs (4) into the spring wells in head section of lock cylinder.
  11. Snap the shutter assembly (5) into the cylinder.
  12. Place the detent spring (6) into the spring well located on side of cylinder.
  13. Carefully place the detent ball (7) on detent spring. Depress the detent ball into the cylinder and assemble into case (8). Detent ball should rest in case slot at front of case.
  14. Align dimples of the cylinder cap (9) with the 4 recesses in the cap. Secure by pressing the cap into place with light hand pressure.
  15. If required, assemble rod clip to lever (10) using the recorded lever information.
  16. Assemble lever to lock. Use e-clip (11) to retain lever assembly.
  17. Insert the key into the lock and function lock to check for proper assembly and smooth operation.