GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC C-Series Medium Duty Truck B7 🢒 General Information 🢒 General Information 🢒 Towing a Disabled Vehicle

When towing a Medium Duty Truck, take the following precautions in order to prevent damage to the vehicle:

    • Use a GM dealer or a professional towing service in order to tow a disabled Medium Duty Truck.
    • Use proper equipment.
    • Follow state and local laws that apply to vehicles in tow.
    • Do not tow vehicles at speeds over 90 km/h (55 mph).
    • Connect the towing components to the main structural parts of the vehicle.
    • Do not attach towing components to the following parts:
       - Bumpers
       - Tow hooks
       - Brackets
    • Only use equipment designed for towing.
    • Follow the instructions given by the tow truck manufacturer.
    • Use a safety chain system.

Front End Towing (Front Wheels off the Ground)

Before Towing

Block the rear wheels of the disabled vehicle. On vehicles with air brakes, release the parking brake system by compressing the brake chamber springs. Refer to Air Brake Chamber Replacement - Front or Air Brake Chamber Replacement - Rear in Air Drums. Releasing the parking brake system prevents the parking brake from engaging while the vehicle is in tow.

On vehicles with hydraulic brakes, release the parking brake fully by moving the lever handle to the fully released position.

Vehicle Towing with the Front Bumper Removed

  1. Remove the front bumper.

    2. Object Number: 200593 Size: SH
  2. Connect and lock the lift chains (2) to the front axle (3), outside of the spring anchor plates (1).

    3. Object Number: 200594 Size: SH
  3. Place an oak beam (3), 1.52 m x 15.2 cm x 15.2 cm (5 ft x 6 in x 6 in), underneath and slightly behind the front spring shackle brackets (4).
  4. Connect the lift chains (2) to the tow bar (1).
  5. Raise the tow bar until the lift chain cinches up and the oak beam seats fully against the spring shackle brackets.
  6. Raise the vehicle to the required height.
  7. Prepare the axles. Refer to Preparing the Axles before Towing the Vehicle in this section.

To Tow a Vehicle with the Front Bumper Installed


    Object Number: 200593 Size: SH
  1. Connect and lock the lift chains (2) to the front axle (3), outside of the spring anchor plates (1).

    2. Object Number: 290689 Size: SH
  2. Place an oak beam (4) underneath and slightly behind the front spring shackle brackets (5).
  3. Connect the lift chains (3) to the tow bar (1).
  4. Take up the slack in the chains until the tow bar is within four inches of the front bumper facing (7).
  5. Place a 5 cm x 30.5 cm (2 in x 12 in) oak boards (2) with rubber pads (6) against the front bumper.
  6. Secure the board.
  7. Remove the remaining slack in the lift chains. The tow bar swing arm should rest against the 2 inch by 12 inch oak board.
  8. Raise the vehicle to the required height.
  9. Prepare the axles. Refer to Preparing the Axles Before Towing the Vehicle.

Preparing the Axles Before Towing the Vehicle

Single Drive Rear Axle

  1. Remove the rear axle shafts. Refer to Rear Axle Disassemble in Rear Drive Axle.
  2. Cover the hub opening in order to prevent loss of the lubricant or lubricant contamination.

After Towing

  1. Block the rear wheels and install the axle shafts. Refer to Rear Axle Disassemble in Rear Drive Axle.
  2. Install the propeller shafts, and inspect the universal joints for proper phasing. Refer to one of the following procedures in Driveline/Axle:
    3.  - Propeller Shaft Replacement - One Piece - Flange Type
     - Propeller Shaft Replacement - One-Piece - Yoke Type
     - Propeller Shaft Replacement - Two Piece - Flange Type
     - Propeller Shaft Replacement - Two Piece - Yoke Type
     - Propeller Shaft Replacement - Three Piece - Flange Type
     - Propeller Shaft Replacement - Three Piece - Yoke Type
  3. Apply the parking brake before disconnecting a Medium Duty Truck from the towing vehicle.
  4. Check and fill the rear axles with oil as required.

Front End Towing (All Wheels on the Ground)

You may tow the vehicle on all wheels, provided that the steering is operable. The power brakes and power steering will not have power assist. Vehicles with air brakes will not have braking capability. Ensure that there is a tow bar between the towing vehicle and the disabled vehicle.

Before Towing

    • Block the wheels of the disabled vehicle.
    • On vehicles with air brakes, release the parking brake system by compressing the brake chamber springs as outlined in Air Brakes. Releasing the parking brake will prevent the parking brake from engaging while in tow.
    • Disconnect the propeller shaft at the rear axle (forward unit on tandem axles). Refer to one of the following procedures in Driveline/Axle:
       - Propeller Shaft Replacement - One Piece - Flange Type
       - Propeller Shaft Replacement - One-Piece - Yoke Type
       - Propeller Shaft Replacement - Two Piece - Flange Type
       - Propeller Shaft Replacement - Two Piece - Yoke Type
       - Propeller Shaft Replacement - Three Piece - Flange Type
       - Propeller Shaft Replacement - Three Piece - Yoke Type
    • Secure the propeller shaft to the frame or the crossmember.
    • If there is damage or suspected damage to the rear axle, remove the axle shafts. Refer to Rear Axle Disassemble .
    • Cover the hub openings in order to prevent loss of lubricant or lubricant contamination.

After Towing

    • Block the rear wheels and install the axle shafts. Refer to Rear Axle Disassemble in Rear Drive Axle.
    • Install the propeller shafts and check for proper phasing of the universal joints. Refer to one of the following procedures in Driveline/Axle:
       - One-Piece Propeller Shaft Replacement
       - Two-Piece Propeller Shaft Replacement
       - Three-Piece Propeller Shaft Replacement
    • Apply the parking brake before disconnecting from the towing vehicle.

Rear End Towing (Rear Wheels Off the Ground)

Before Towing

    • Secure the steering wheel in order to maintain a straight-ahead position.
    • Ensure that the front axle is not loaded above the front axle Gross Axle Weight Rating (GAWR).
    • The GAWR is located on the Vehicle Certification Label.

After Towing

    • Block the rear wheels and release the steering.
    • Apply the parking brake before disconnecting from the towing vehicle.
    • Inspect the fluid level in the rear axle.
    • Fill the axle fluid as necessary.

Special Towing Instructions
    • Call a local GM dealer or professional towing service.
    • Follow all the state and local laws regarding towing:
       - Warning signals
       - Night illumination
       - Speed
    • Do not tow any vehicle over 90 km/h (55 mph).
    • If a vehicle is damaged, secure any loose or protruding parts prior to towing.
    • Use a safety chain system that is completely independent of the primary lifting and towing attachment.
    • Do not go underneath a raised vehicle unless the vehicle is supported by safety stands.
    • Do not perform any towing operation that may risk the safety of the tow truck operator, bystanders or other motorists.