Front Axle - Actuator Does Not Engage
88chevy03GMC NUMBER: 88-T-87
GROUP: 4C - Front Axle
DATE: March, 1988
CORPORATE
NUMBER: 864302
SUBJECT: FRONT AXLE ACTUATOR
MODELS: 1988 K MODEL
THIS BULLETIN SUPERCEDES DCS MESSAGE 1988 K-1, 2, 3 SIERRA TRUCKS DATED JANUARY 6,1988
PARTS WILL BE AVAILABLE FROM GMSPO ON MARCH 15, 1988
If the front axle does not engage or becomes disengaged while the vehicle is operated in 4 high or 4 low and diagnosis indicates that replacement of the front axle actuator is necessary, use the following parts and instructions:
From start of production through
VIN# JE524063 Pontiac Production
JE535372 Fort Wayne Production
J1551431 Oshawa Production
Repair by replacing both the thermal actuator and the fork damper assembly.
Use: Actuator Assembly P/N 26013495
Fork Damper Assembly P/N 26013507
Production began using the fork damper assembly with the vehicle identification number breakpoints listed above. After these VIN's, repair with actuator assembly only.
Actuator Assembly P/N 26013495
The fork damper assembly reduces back pressure and the new actuator is a new part. Used together, these parts increase actuator life.
FIGURE 1:
SERVICE PROCEDURE
Thermal Actuator Replacement
Remove and disconnect
1. Disconnect electrical wire from black junction located on axle tube.
2. Unscrew actuator (Figure No. 1, item 16).
Install and connect
1. Install replacement actuator (Figure No.1, item 16). Tighten to 22 N-m (16 ft.lbs.).
2. Connect wire to black junction on axle tube.
Fork Damper Assembly Replacement
Raise truck and support using suitable safety stands.
Remove or disconnect
1. Actuator connector.
2. Indicator light connector.
3. Drive axle to tube bolts.
4. Axle mounting nuts.
5. Nut from the idler arm.
6. Nut from pitman arm. Push the relay rod up and toward the front of the truck. Turn wheel out to loosen the drive shaft from the axle tube. Move axle shaft away from the axle tube and secure out of the way.
7. Stabilizer shaft link, if present.
8. Skid plate, if present.
9. Drain plug from the carrier and drain the axle lubricant.
10. Axle tube to carrier bolts.
11. Axle tube from carrier. Take care to keep the open end of the tube up.
FIGURE 1:
12. Shift lever and fork. (Spring #13 in Figure No. 1 and clip #11 will not be in existing tube and are part of new fork damper assembly).
Install or connect
1. Shift lever, fork, spring and clip assembly into carrier case (Assembly P/N 26013507). Install spring (#10 in Figure No. 1) on shift lever. Clean mating surfaces of the axle tube and carrier assembly. Remove all oil and grease. Use carburetor cleaner or equivalent. Apply a bead of sealer (GM P/N 1052942, Loctite 518, or equivalent) to the tube sealing surface.
2. Axle tube to carrier.
3. Axle tube to carrier bolts and tighten to 40 N-m (30 ft.lbs.).
4. Drive shaft to axle shaft.
5. Drive shaft to axle shaft bolts and tighten to 80 N-m (59 ft.lbs.).
6. Axle mounting nuts with washers. Tighten to 80 N-m (59 ft.lbs.).
7. Relay rod to idler arm and pitman arm.
8. Idler arm washer and nut.
9. Pitman arm washer and nut. Tighten pitman arm and idler arm nuts to 54 N-m (40 ft.lbs.).
10. Stabilizer shaft link, if present.
11. Actuator connector.
12. Indicator connector.
13. Drain plug and the washer. Tighten plug to 32 N-m (24 ft.lbs.).
14. New lubricant. Refer to "Specifications" Manual X-8731, pg. 4C-6.
15. Filler plug. Tighten plug to 32 N-m (24 ft. lbs.).
16. Skid plate, if present.
17. Skid plate torx head screws. Tighten screws to 34 N-m (25 ft.lbs.).
Lower Truck.
For warranty replacement of the thermal actuator only use:
Labor Op. F0025 Time 0.3 hrs
For warranty replacement of the thermal actuator and fork damper assembly use:
Labor Op. T7525 Time 1.1 hrs