GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C6/C7/C8 🢒 Body Repair 🢒 Bolted Exterior Body Panels and Closures 🢒 Cab Replacement

Removal Procedure

    Object Number: 815540 Size: SH

    Important: The cab replacement procedure will vary depending upon the optional equipment on the vehicle.

  1. Tag all of the following components during removal in order to ensure correct installation:
    2. • The lines
    • The wires
    • The hoses
    • The harnesses
  2. Block the wheels.
  3. Roll down the windows.
  4. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  5. Remove the hood. Refer to Hood Layer Removal .

    6. Object Number: 882676 Size: SH
  6. Remove the wheel housing panels. Refer to Wheelhouse Panel Replacement .
  7. Remove the radiator support braces and the bolts from the brackets at the front of the cab.
  8. Remove the underhood fuse block cover and 2 bolts. Refer to Instrument Panel Carrier Replacement .
  9. Remove the battery cable from the underhood fuse block. Refer to Battery Negative Cable Disconnection and Connection .
  10. Remove the vehicle control module (VCM) wiring harness at the right of the front of the cowl in the engine compartment:
    11. 10.1. Disconnect the wiring harness from the VCM behind the instrument panel (I/P) storage compartment.
    10.2. Remove the screw holding the wiring harness to the cowl in the engine compartment. Refer to Instrument Panel Carrier Replacement .
    10.3. Push the harness through the grommet in the cowl.
  11. Remove the starter relay connector at the lower right side of the cowl.
  12. Remove the air conditioning lines. Refer to Air Conditioning Evaporator Tube Replacement - Inlet and Air Conditioning Evaporator Tube Replacement - Outlet .
  13. Remove the heater hoses at the cowl. Refer to the following procedures:
    14. •  Heater Inlet Hose Replacement
    •  Heater Outlet Hose Replacement
  14. Remove the radio antenna. Refer to Fixed Antenna Mast Replacement .
  15. If you are replacing the cab, remove the outer hood seal above the bumper bracket. Refer to Hood Rear Seal Replacement .

    16. Object Number: 206472 Size: SH
  16. Remove the steering column bolt at the steering gear.
  17. Remove the power steering lines. Refer to Power Steering Fluid Reservoir Inlet Hose Replacement and Power Steering Fluid Reservoir Outlet Hose Replacement .
  18. Remove the lower wiring harness from the bulkhead connector at the left side of the cowl in the engine compartment:
    19. 18.1. Remove the 2 bolts at the connector in the engine compartment.
    18.2. Disconnect the wiring connectors in the cab.
    18.3. Push the harness into the engine compartment.
  19. If the vehicle has a manual transmission, perform the following steps:
    20. 19.1. Remove the clutch control cable from the transmission. Refer to Clutch Cable Replacement .
    19.2. Remove the shift lever at the top of the transmission.
             19.2.1. Remove the cotter pin at the end of the pin.
             19.2.2. Tap out the pin.
    19.3. Shift the cable linkage at the transmission.
    19.4. Remove the shift tower from the floor of the cab, with the following procedure:
             19.4.1. Remove the 4 bolts holding the tower to the floor.
             19.4.2. Trace the electrical wire from the base of the tower to the connector behind the heater.
             19.4.3. Disconnect the connector.
             19.4.4. Lift the wire from under the floor mat.
  20. If the vehicle has air brakes, perform the following steps. Refer to Tractor Air Brake Park Control Valve Replacement :
    21. 20.1. Number the vacuum lines at the brake application valve.
    20.2. Remove the air lines at the cowl, with the following procedure:
             20.2.1. Use a wrench in order to grasp each line.
             20.2.2. Push in the line.
             20.2.3. Push the wrench against the collar on the connector in order to release the line.
  21. If the vehicle has hydraulic brakes, perform the following procedure in order to remove the power assist unit. Refer to Power Brake Booster Replacement :
    22. 21.1. On the engine compartment side, remove the 2 nuts at the top of the unit.
    21.2. From inside the cab, remove the 2 bolts at the bottom of the unit holding the unit to the cowl.
    21.3. Disconnect the 4 wiring connectors at the unit.
  22. If the vehicle has an air seat, remove the air seat supply line to the storage cylinder inside the frame rail and behind the cab. Refer to Air Suspension Seat Replacement .
  23. Remove the air horn from the roof. Refer to Air Horn Replacement .
  24. Remove the fuel vapor canister line in the component box under the left side of the cab. Refer to Evaporative Emission Hoses/Pipes Replacement - Canister/Fuel Tank .

    25. Object Number: 818850 Size: SH
  25. Remove the nut and the washer at the bottom of each front cab mount from under the bracket on the side rail.

    26. Object Number: 818854 Size: SH
  26. Remove the 6 bolts holding the support bracket at the rear of the cab to the rear crossmember.

    27. Remove the nuts from under the crossmember.


    Object Number: 206475 Size: SH
  27. Remove the cab from the chassis using the lifting straps:

    28.         Important: Remember that the trimmed cab weighs about 454 kg (1,000 lb).

    27.1. Use 4 commercial lifting straps. Ensure that the straps are 152 mm (6 in) wide and 3 m (10 ft) long.
    27.2. Wrap one strap around each of the hood bumper brackets at the front of the cab.

            Notice: When the cab is being removed, ensure that the lifting straps are not wrapped around the door frames. Otherwise, damage to the window channels may occur.

    27.3. Pass one strap into the cab through the door on each side at the top rear of the window openings.
    27.4. Connect the 2 straps together in the center.
    27.5. Close the doors.
  28. Walk around the cab in order to ensure that all components are disconnected from the chassis.
  29. Slowly raise the cab.

    30. Object Number: 206477 Size: SH
  30. With the aid of an assistant, guide the cab while the cab is lifting.

Installation Procedure
  1. Block the chassis wheels.

    2. Object Number: 206477 Size: SH
  2. Use the following procedure in order to install the cab onto the chassis.
    3. 2.1. Use the following procedure in order to attach the lifting straps to the cab:

            Important: Remember that the trimmed cab weighs about 454 kg (1,000 lb).

             2.1.1. Use 4 commercial lifting straps. ensure that the straps are 152 mm (6 in) wide and 3 m (10 ft) long.
             2.1.2. Wrap one strap around each of the hood bumper brackets at the front of the cab.

                       Notice: When the cab is being removed, ensure that the lifting straps are not wrapped around the door frames. Otherwise, damage to the window channels may occur.

             2.1.3. Pass one strap into the cab through the door on each side at the top rear of the window openings.
             2.1.4. Connect the 2 straps together in the center.
             2.1.5. Close the doors.
    2.2. Guide the long bolts in the cab floor through the cab mounts.

    Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 818850 Size: SH
  3. Install the washer and the nut to each front cab mount bolt from under the bracket on the frame rail.

    4. Tighten
    Tighten the nut to 76 N·m (56 lb ft).


    Object Number: 818854 Size: SH
  4. Install the 4 nuts and bolts to the rear cab mounting bracket attaching the cab to the frame crossmember.

    5. Tighten
    Tighten the nuts to 70 N·m (52 lb ft).

  5. Install the air horn onto the roof. Refer to Air Horn Replacement .
  6. If the vehicle has hydraulic brakes, use the following procedure in order to install the power assist unit, and refer to Power Brake Booster Replacement :
    7. 6.1. Use the 2 nuts in order to finger-tighten the power assist unit to the 2 studs on the cowl.
    6.2. Install the 2 nuts finger tight through the base of the unit from within the cab.
    6.3. Connect the wiring connectors.

    Tighten
    Tighten the brake assist unit nuts to 28 N·m (21 lb ft).

  7. If the vehicle has air brakes, install the air lines at the brake application valve. Push each line into the fitting. Refer to Air Brake Application Valve Replacement .
  8. If the vehicle has an automatic transmission, perform the following procedure in order to install the shift tower to the cab floor:
    9. 8.1. Run the electrical line under the floor mat.
    8.2. Connect the electrical line behind the heater.
    8.3. Use the 4 bolts in order to install the shift tower to the floor.

    Tighten
    Tighten the bolts to 6 N·m (53 lb in).

  9. If the vehicle has a manual transmission, perform the following procedure in order to install the shift linkage:
    10. 9.1. Install the transmission cable linkage to the side of the transmission.
    9.2. Use the cotter pin in order to install the shift lever to the top of the transmission.
    9.3. Install the clutch control cable to the transmission. Refer to Clutch Cable Replacement .
  10. If the vehicle has a diesel engine, install the throttle control valve.
  11. Pass the wiring harness through the lower bulkhead pass-through at the left side of the cowl.
  12. Use the 2 bolts in order to attach the harness. Connect the wiring.

    13. Object Number: 206472 Size: SH
  13. Install the steering column bolt at the steering gear.

    14. Tighten
    Tighten the bolt to 62 N·m (46 ft lb).

  14. Install the power steering lines. Refer to Power Steering Fluid Reservoir Inlet Hose Replacement and Power Steering Fluid Reservoir Outlet Hose Replacement .
  15. If the vehicle has an air seat, install the air seat supply line to the storage cylinder behind the cab at the left frame rail. Refer to Air Suspension Seat Description .
  16. Install the fuel vapor canister lines to the component box below the left side of the cab. Refer to Evaporative Emission Hoses/Pipes Replacement - Canister/Fuel Tank .
  17. Install the radio antenna. Refer to Fixed Antenna Mast Replacement .
  18. Install the outer hood seal. Refer to Hood Rear Seal Replacement .
  19. Install the heater hoses to the heater core tubes. Refer to the following procedures:
    20. •  Heater Inlet Hose Replacement
    •  Heater Outlet Hose Replacement
  20. Install the air conditioning lines. Refer to Air Conditioning Evaporator Tube Replacement - Inlet and to Air Conditioning Evaporator Tube Replacement - Outlet .
  21. Install the VCM wiring harness to the right side of the cowl in the engine compartment:
    22. 21.1. Push the harness through the grommet in the cowl.
    21.2. Use a screw in order to attach the wiring harness.
    21.3. Route the harness to the VCM behind the instrument panel compartment.
    21.4. Connect the 2 connectors to the I/P wiring harness near the VCM.
  22. Reconnect the battery cable to the underhood fuse block. Refer to Battery Negative Cable Disconnection and Connection .
  23. Use the 2 bolts in order to install the junction block cover.
  24. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  25. Install the following components to the brackets at the front of the cab:
    26. • The radiator support braces
    • The bolts

    Object Number: 882676 Size: SH
  26. Install the inner fender. Refer to Wheelhouse Panel Replacement .
  27. Install the clip retaining the front of the fender to the radiator support bracket. Refer to Wheelhouse Panel Replacement .

    28. Object Number: 815540 Size: SH
  28. Install the hood. Refer to Hood Layer Installation .
  29. Before starting the engine, inspect the following components for secure connections:
    30. • The wires
    • The lines
    • The control linkage
    • The generator wires
    • The starter motor wires
    • The battery cables. Refer to Battery Negative Cable Disconnection and Connection .
  30. Start the engine.
  31. Inspect all connections and linkage.