GM Service Manual Online
For 1990-2009 cars only

Consult your dealer/retailer or a professional towing service to have the vehicle towed. They can provide the right equipment and know-how to tow it without damage. See Roadside Assistance Program.

Releasing Air-Operated Parking Brakes

If the vehicle has air brakes, there could be a special towing problem. If the vehicle has to be towed because of a complete loss of air pressure from both systems, the parking brakes will have automatically engaged. The tow operator can release the brakes manually by using the following steps. Then the vehicle can be towed with all wheels or only the rear wheels on the ground.

  1. Block the wheels of the vehicle.

  2. Object Number: 811003  Size: B3
  3. Remove the release stud and nut from the side of the brake chamber. Some chambers have studs which are visible at all times.

  4. Object Number: 807531  Size: A3
  5. Remove the rubber cap from the rear of the chamber.
  6. Put the release stud, nut and flat washer into the chamber.
  7. Turn the stud clockwise a quarter of a turn.

  8. Object Number: 807532  Size: A3
  9. Turn the stud nut clockwise several turns to release the brakes. Follow the same procedure to release the other brake or brakes.
  10. At the repair facility, apply air pressure of at least 70 psi (480 kPa) to the brake chambers, either from an external air supply or the vehicle's air system.
  11. Turn the stud nut counterclockwise several turns. Remove the stud from the chamber.
  12. Replace the stud and washer and tighten the nut into the side of the chamber.
  13. Replace the rubber cap.