Assembling and Coding the Endgate Lock Cylinder

The endgate lock cylinder uses seven tumblers positions 3 through 9. The tumbler positions are staggered on both sides of the lock cylinder five on one side and three on the other.

Fig 1: View Of Door Lock Cylinder Components
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: The lock cylinder tumblers are not self-retaining. Hold the tumblers in place when the key is not in the lock cylinder. Hold the lock cylinder tumblers (8) in place when performing this procedure.
1. Hold the cylinder (6) so that the side with five tumbler openings are up.
2. Insert five tumbler springs (7) into the five spring wells.
3. Install the tumbler (8) for position 4 in the slot nearest to the front of the lock cylinder.
4. Install the 3 remaining tumblers (8) for positions 6, 8 and 10 in the lock cylinder.
5. Press the tumblers into place with light hand pressure.
6. Insert the key into the lock cylinder (6). If the tumblers are not flush with the lock cylinder, remove the tumblers and perform the coding procedure again.
IMPORTANT: Hold the tumblers in place before removing the key.
7. Rotate the lock cylinder (6) so that the side with 3 tumbler openings are up.
8. Insert 3 tumbler springs (7) into the 3 spring wells.
9. Install the tumbler for position 5 into the slot nearest the front of the lock cylinder.
10. Install the 2 remaining tumblers for positions 7 and 9 in the lock cylinder.
11. Press the tumblers into place with light hand pressure.
12. Insert the key into the lock cylinder (6). If the tumblers are not flush with the lock cylinder, remove the tumblers and perform the coding procedure again.
13. Lubricate the tumblers using GM P/N 12346241 or equivalent.
14. If necessary, perform the following steps to install the shudder door.
    • Install the 2 plate springs (3) into the 2 spring wells in the head of the lock cylinder (6).
    • Press the shutter (2) into the lock cylinder until it snaps into place.
15. Insert the key into the lock cylinder (6). If the lock cylinder does not rotate in the lock cylinder housing, disassemble the lock cylinder and perform the coding procedure again.
16. Install the lock cylinder spring (9) to the lock cylinder.
17. Install the lock cylinder spring retainer (8) to the lock cylinder.
18. Remove the key from the lock cylinder (5).
19. Install the lock cylinder cap (1) by pressing the cap onto the lock cylinder with light hand pressure.