Front Side Door Lock Cylinder Coding

Fig 1: Exploded View Of Front Side Door Lock Cylinder Components

Courtesy of GENERAL MOTORS COMPANY

The free-wheeling door lock cylinder only uses six of the eight cut positions, 5 through 10 (when counting from the key head). The tumbler positions are staggered from side to side and 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 (1) is assembled into the case (4).

NOTE:

All lock cylinders for side milled keys have right and left tumblers. The location of the tooth of the tumbler determines whether it is right or left. All tumblers are marked 1R, 1L, 2R, 2L, etc. The number is cut depth and the letter identifies right or left. Tumblers identified as 1L to 4L must be inserted in the cylinder side where the first spring pocket is nearest to the back of the key head, tumblers identified as 1R to 4R must be inserted in the opposite side.

1. Hold the cylinder (1) positioned so the side with the tumbler spring pocket nearest to the cylinder head faces up.
2. Insert one tumbler spring (2) into each of the three spring pockets.
3. The first tumbler to be loaded will be the key cut position number 3 (the third number in the key code). Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the lock cylinder assembly (the end where the key is inserted).
4. In the same manner, determine the cut depth and corresponding tumbler and install the two remaining tumblers (3) into the tumbler slots located at key cut positions 5 and 7.
5. Check the correct loading by holding the tumblers (3) in position and fully inserting the key into the cylinder (1). All tumblers should be flush with the outside diameter of the cylinder.
6. Rotate the cylinder (1) so the tumbler spring pockets on the opposite side are facing up and then remove the key. Remember the tumblers (3) are not self-retained and must be held in place.
7. Insert one tumbler spring (2) into each of the three spring pockets.
8. The first tumbler to be loaded will be the key cut position number 4. Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the lock cylinder assembly.
9. In the same manner, determine the cut depth and corresponding tumbler and install the two remaining tumblers (3) into the tumbler slots located at key cut positions 6 and 8.
10. Check the correct loading by holding the tumblers (3) in position and fully inserting the key into the cylinder (1). All tumblers should be flush with the outside diameter of the cylinder.
11. Lightly lubricate the tumbler (3) surfaces using the grease provided.
12. With the key fully inserted into the cylinder assembly, install the cylinder (1) into the case (4). Hold the lever and case (4) while pressing in on the cylinder (1) and rotate 90°.
13. Remove the key being careful to ensure the cylinder (1) is locked into the case (4).
14. Install the lock cylinder cap (5) by aligning the open window of the cap with the corresponding protrusion area of the case (4). Snap the cap into place with light hand pressure. Be sure the cap is securely retained on the case.