Locks: Service and Repair
Key and Lock Cylinder Coding
Door Lock Cylinder
The front side door lock cylinder uses 8 of the 10 key cut positions, 3-10 when counting from the key head. The tumbler orientations alternate in adjacent locations from side to side with 4 tumblers on each side.
Note: The front side door lock cylinder tumblers (3) are not self retaining and must be held in place if the key is not fully inserted in the lock cylinder, or until the lock cylinder (1) is assembled into the case assembly (4).
1. Hold the uncoded cylinder (1) positioned so the side of rotational stop lug is facing downward, as shown.
2. Insert one tumbler spring (2) each into the 4 holes from the upper side.
Note: The GM codebook number is not the same value as those stamped on the tumblers, i.e. GM number 1 = tumbler number 4, GM number 2 = tumbler number 3, GM number 3 = tumbler number 2, and GM number 4 = tumbler number 1.
3. The first tumbler to be loaded will be key cut position number 3, the third number in the key code.
4. Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the rotor-CP.
5. In the same manner, determine the cut depth and corresponding tumbler and install the 3 remaining tumblers (3) into the tumbler slots located at key cut positions 5, 7, and 9.
6. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the rotor. All the tumblers should be flush with the outside diameter of the rotor.
7. Rotate the cylinder (1) so that the side with the rotational stop lug is facing upward and then remove the matching key. Remember the tumblers (3) are not self retaining and must be held in place.
8. Insert one tumbler spring (2) each into the 4 tumbler spring holes.
9. The first tumbler to be loaded will be 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 rotor-CP.
10. In the same manner, determine the cut depth and corresponding tumbler and install the 3 remaining tumblers (3) into the tumbler slots located at key cut positions 6, 8, and 10.
11. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the rotor (1). All tumblers should be flush with the outside diameter of the rotor (1).
12. Lightly lubricate tumbler (3) and cylinder (1) surfaces using the lubrication provided.
13. With the matching key fully inserted into coded cylinder, install the coded cylinder into the case (4) fully. Make sure the cylinder is stopped at approximately 60 degrees when rotated with the key, approximately 120 degrees total.
14. Remove the key, the cylinder stays in the case, and install the lock cylinder cap (5) on the case (4). Crimp the side edge of the lock cylinder cap (5) around the case depressions (2 places).
15. Hold the cylinder assembly so the key opening is facing down (6 o'clock), and the cylinder cut out is facing you, so the tumblers are visible.
16. Keep the cylinder assembly in the same orientation as above, key opening at 6 o'clock, rotor top at 12 o'clock. The return spring consists of a lower and upper spring tab. Locate the lower spring tab to the left side of the cylinder tab. This cylinder tab is located at the 12 o'clock position and resembles a hook shape. No force is required against spring tension. Then, working against spring tension, rotate the upper spring tab to the right side of the cylinder tab. The upper spring tab will finally reside in the hook shape of the cylinder tab.
17. Keep the cylinder in the same orientation as above, key opening at 6 o'clock, rotor top at 12 o'clock. Orient the lever (7) with the tab at facing down at 6 o'clock. Lower the lever (7) onto the rotor top so the tab fits between the spring tab upper and spring tab lower.
18. Install the retaining ring (8) in the grove at the end of the cylinder (1) to secure the lever (7) to the cylinder. Concave surface of the retaining ring (8) should touch the lever.
19. Install the clip (9) as shown.
Ignition Lock Cylinder
This vehicle has two different types of ignition lock cylinders based on what type of steering column the vehicle is equipped with. The electric power steering (EPS) option, usually found on 4 cylinder models, and the non EPS, usually found on 6 cylinder models, use different ignition lock cylinder designs.
The ignition lock cylinder uses all 10 key cut positions, 1-10 when counting from the key head. The tumbler orientations alternate in adjacent locations from side to side with 5 tumblers on each side.
Note: The ignition lock cylinder tumblers (1) are not self retaining and must be held in place if the key is not fully inserted in the lock cylinder (2), or until the lock cylinder (2) is assembled into the case assembly (5).
1. Hold the uncoded cylinder assembly (2) positioned so the side with the security plug (3) faces to the left of the key head.
2. Insert one tumbler spring (7) into each of the 4 tumbler spring holes.
3. The first tumbler (1) to be loaded will be key cut position 1, the first number in the key code. Install this tumbler in the tumbler slot closest to the head of the lock cylinder (2), the end where the key is inserted.
4. Advancing one tumbler slot at a time, install tumblers 3, 5, and 7 sequentially on the same side as tumbler 1.
5. Turn the lock cylinder over and insert one tumbler spring (7) into each of the 4 tumbler spring holes on the opposite side of the lock cylinder.
6. Insert tumbler 2 into the tumbler slot closest to the head of the lock cylinder (2), the end where the key is inserted.
7. Advancing one tumbler slot at a time, install tumblers 4, 6, and 8 sequentially on the same side as tumbler 2.
8. Check for correct tumbler loading by holding the tumblers (1) in position and inserting the correct key into the lock cylinder. All tumblers (1) should be flush with the housing of the lock cylinder.
9. Lightly lubricate the tumblers and small detent recessed areas the tumblers are in with GM Super Lube GM P/N 12346241 or equivalent light lithium grease.
10. Take the slide piece and insert into the rotor. Ensure "Front of Sliding Piece" is facing the front face of the rotor. If the slide piece is installed incorrectly, the key cannot insert into the rotor due to no access to the ramp.
11. Install the pivot pin into the actuator lever and install the actuator lever into the ignition lock cylinder housing. Ensure that the actuator lever is inside of the lock cylinder housing at the end close to key insertion opening. Actuator lever should pivot on the pin against spring tension.
12. Insert the key into the coded lock cylinder (2) and hold the lock cylinder positioned so the side with the security plug (3) faces to the left of the key head.
13. Hold the ignition lock housing positioned so the security plug actuator lever (3) also faces to the right of the key head.
14. Push the exposed end of the security plug actuator lever (3) toward the center of the lock cylinder housing (1) and hold it. Insert the coded lock cylinder (2) with the key in it into the ignition lock cylinder housing (1) until the cap is flush with the housing.
15. Rotate the keyed lock cylinder counterclockwise slightly until it stops and detents outward slightly. The key should be able to be removed and the lock cylinder should remain in the housing.
16. Install the retaining clip (1) onto the coded lock cylinder where it comes out of the back of the lock cylinder housing.
Endgate Lock Cylinder
The endgate lock cylinder uses 8 of the 10 key cut positions, 3-10 when counting from the key head. The tumbler orientations alternate in adjacent locations from side to side with 4 tumblers on each side.
Note: The endgate lock cylinder tumblers (3) are not self retaining and must be held in place if the key is not fully inserted in the lock cylinder, or until the lock cylinder (1) is assembled into the case assembly (4).
1. Hold the uncoded cylinder (1) positioned so the side of rotational stop lug is facing downward, as shown.
2. Insert one tumbler spring (2) each into the 4 holes from the upper side.
Note: The GM codebook number is not the same value as those stamped on the tumblers, i.e. GM number 1 = tumbler number 4, GM number 2 = tumbler number 3, GM number 3 = tumbler number 2, and GM number 4 = tumbler number 1.
3. The first tumbler to be loaded will be key cut position number 3, the third number in the key code.
4. Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the cylinder (1).
5. In the same manner, determine the cut depth and corresponding tumbler and install the 3 remaining tumblers (3) into the tumbler slots located at key cut positions 5, 7, and 9.
6. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the rotor. All the tumblers should be flush with the outside diameter of the rotor.
7. Rotate the cylinder (1) so that the side with the rotational stop lug is facing upward and then remove the matching key. Remember the tumblers (3) are not self retaining and must be held in place.
8. Insert one tumbler spring (2) each into the 4 tumbler spring holes.
9. The first tumbler to be loaded will be 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 rotor-CP.
10. In the same manner, determine the cut depth and corresponding tumbler and install the 3 remaining tumblers (3) into the tumbler slots located at key cut positions 6, 8, and 10.
11. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the rotor (1). All tumblers should be flush with the outside diameter of the rotor (1).
12. Lightly lubricate tumbler (3) and cylinder (1) surfaces using the lubrication provided.
13. With the matching key fully inserted into coded cylinder, install the coded cylinder into the case (4) fully. Rotate the key to ensure proper operation of the cylinder.
14. With the cylinder (1) inserted in the case (4), pull the cylinder (1) out of the case (4) slightly and rotate it until the check ball well is exposed at the back of the case (4). Insert the check ball spring (6) and check ball (7) and hold the check ball (7) in position as the cylinder is rotated, concealing the check ball (7) in the case (4).
15. Remove the key, the cylinder stays in the case, and install the lock cylinder cap (5) on the case (4). Crimp the side edge of the lock cylinder cap (5) around the case depressions (2 places).
16. Hold the cylinder assembly so the key opening is facing down (6 o'clock), and the cylinder cut out is facing you, so the tumblers are visible.
17. Keep the cylinder in the same orientation as above, key opening at 6 o'clock, rotor top at 12 o'clock. Orient the lever (8) with the tab at facing down at 6 o'clock. Lower the lever (8) onto the rotor top.
18. Install the retaining ring (9) in the grove at the end of the cylinder (1) to secure the lever (8) to the cylinder. Concave surface of the retaining ring (9) should touch the lever.
19. Install the clip (10) as shown.