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Tim's Auto Repair
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1991 s10 blazer 4wd wont engage- new vacume switch, transfer

Resolved Question:

1991 s10 blazer 4wd won't engage- new vacume switch, transfer case switch, good vacume to transfer case switch, good actuation of vacume switch.
Submitted: 7 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 7 years ago.


the shift cable may have come loose from the shift fork on the differential


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Shift Cable Replacement


  1. Shift cable from the vacuum actuator.



  1. Bend the tang on the lock spring as shown.
  2. Push the diaphragm in to release the cable end.



  1. Squeeze the two locking fingers of the cable ferrule with pliers. Then pull the cable from the bracket.
    • Raise the vehicle and support with safety stands.



  1. Bolts.
    • DO NOT unscrew the coupling nut at this time.
  1. Shift cable housing from the carrier assembly. Pull out about 20 mm (3/4 inch) .
  2. Cable end from the shift fork shaft. Bend the tang of the locking spring as shown, then pull the cable end from the shift fork shaft.
  3. Shift cable from the shift cable housing by unscrewing the coupling nut.
  4. Shift cable from the vehicle.


  1. Shift cable housing to the carrier assembly.
  2. Bolts.
    • Tighten bolts to 48 Nm (36 ft. lbs.) .



  1. Shift cable to the shift cable housing.
    1. The shift cable must be attached to the housing before it is routed.
    2. Guide the cable end through the hole in the shift cable housing.
    3. Push the cable end into the shift fork shaft. It should snap into place.
    4. Thread the coupling nut into the housing by hand to avoid cross threading.
    • Tighten:
    • Coupling nut to 10 Nm (90 inch lbs.) .
    • Lower the vehicle.
  1. Shift cable to the vehicle.
    • Route as shown.
  1. Shift cable to the vacuum actuator.



  • Push the cable into the hole in the bracket. The cable end and ferrule should snap together.
Differential Carrier


4x4 Front Axle Components
Axle Components - Legend



  1. Unlock the steering column so the linkage is free to move.



  1. Disconnect the shift cable from the vacuum actuator.
  2. Battery and battery tray.
  3. Raise the vehicle and support with safety stands.
  4. Front wheels.



  1. Steering linkage shield, if equipped.



  1. Differential carrier shield, if equipped.



  1. Drain plug and flat washer.
    • Drain lubricant from carrier.
  1. Right side lower shock bolt.
  2. Wire from indicator switch.
  3. Shift cable housing and shift cable from the carrier housing.
  4. Vent hose.
  5. Steering relay rod from idler arm and pitman arm. IMPORTANT: It is essential that the positions of all driveline components relative to the propeller shaft and axles be observed and accurately reference marked prior to disassembly. These components include the propeller shafts, drive axles, pinion flanges, output shafts, etc. All components must be reassembled in the exact relationship to each other as they were when removed. Additionally, the published specifications and torque values, as well as any measurements made prior to disassembly must be followed.
  6. Bolts.
    • Remove the drift from the brake rotor.
  1. Bolts and nuts.
  2. Front propeller shaft with a quick tug to disengage retaining ring.
    • Support both lower control arms with suitable stands at edge of stabilizer shaft. Lower vehicle until front end weight is resting on stands.
  1. Bolts and nuts.
    • Hold the upper nut with an 18 mm wrench inserted through the frame.
  1. Carrier assembly. Roll the carrier counterclockwise while lifting up to gain clearance from the mounting ears.
  2. Tube bolts from carrier.


4x4 Front Axle Components
Axle Components - Legend


  1. Tube assembly.
  2. Tube assembly bolts to carrier assembly.
  3. Carrier assembly to the vehicle.
  4. Bolts and nuts.
    • Tighten bolts to 103 Nm (76 ft. lbs.) or nuts to 75 Nm (55 ft. lbs.) .
  1. Upper mounting bolt, washer, and nut.
    • Tighten bolts to 48 Nm (36 ft. lbs.) .



  1. Front propeller shaft retainers and bolts.
    • Tighten bolts to 20 Nm (15 ft. lbs.) .
  1. Bolts.
    • Install one bolt finger tight.
    • Rotate the axle shaft to install the remaining bolts.
    • Hold the axle by inserting as drift in the top of the brake caliper and into the vanes of the brake rotor.


  • Bolts to 80 Nm (60 lb. ft.).
  • Remove the drift from the brake rotor.
  1. Vent hose.
  2. Idler and pitman arms to steering relay rod.
  3. Shaft and tube assembly.
  4. Indicator switch wire.



  1. Shift cable to shift cable housing.
  2. Lower shock bolt and nut.


  • Axle lubricant level.
  1. Drain plug and flat washer.
    • Tighten plug to 33 Nm (24 ft. lbs.) .
  1. Under body shield, if equipped.
  2. Tires and wheels.
    • Remove safety stands and lower vehicle.
  1. Shift cable to vacuum actuator.
  2. Battery tray and battery.
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