Product Safety - Auto-Apply Park Brake Performance

Some 1994-1999 GMC C-Series and 1997-1998 T-Series Medium Duty Trucks equipped with the auto-apply park brake (RPO J71) and sold for use in Canada may exhibit certain malfunctions that generally may cause the park brake to operate in the as-designed failure mode. These malfunction conditions are as follows:

The first condition can cause an unintended park brake apply at speed. By design, the auto-apply park brake will apply as a fail-safe mode if any power interruption or fluid pressure loss occurs. If this occurred, the Park Brake warning lamp would illuminate, and there would be a noticeable deceleration of the vehicle. There would be no loss of vehicle control and the driver could bring the vehicle to a safe stop at the side of the road. The second condition could cause a slow apply or release of the park brake. The general system requirement for apply or release is 3 to 5 seconds. Longer times (10 seconds) could occur if the reservoir fluid temperature is above 55°C (130°F) or below -18°C (0°F). There is a warning in the Owner's Manual that the driver should not exit the vehicle until the park brake has fully set and the red warning light indicating this has illuminated. Both conditions could cause a failure to release the park brake when the vehicle is parked. Failure to release is a warning feature to prevent damage and should be an indication to the operator to have the vehicle system checked for abnormalities.

As a result of these conditions and their consequences described above, Transport Canada has informed General Motors of Canada Limited that it believes a safety defect exists in these vehicles. General Motors of Canada Limited has agreed to rectify the conditions by conducting a safety campaign.

To help prevent the possibility of these conditions occurring, dealers are to seal the parking brake pump and the reservoir. Some C-Series vehicles are to also have a more durable solenoid installed (T-Series and some C-Series vehicles are already equipped with this solenoid). Included with their notification, owners will receive an updated maintenance schedule to insert into their Owner's Manual (see the copy at the end of this bulletin).

Involved are certain 1994-1999 GMC C-Series and 1997-1998 T-Series Medium Duty Trucks equipped with auto-apply park brakes (J71) and sold for use in Canada and built within the following VIN breakpoints:

Involved vehicles have been identified by Vehicle Identification Number. Computer listings containing the complete Vehicle Identification Number, customer name and address data have been prepared, and are being furnished to involved dealers with the campaign bulletin. The customer name and address data furnished will enable dealers to follow-up with customers involved in this campaign. Any dealer not receiving a computer listing with the campaign bulletin has no involved vehicles currently assigned.

These dealer listings may contain customer names and addresses obtained from the Inter-Provincial Records. The use of such motor vehicle registration data for any other purpose is a violation of provincial laws. Accordingly, you are urged to limit the use of this listing to the follow-up necessary to complete this campaign.

Parts required to complete this campaign are to be obtained from General Motors Service Parts Operations (GMSPO). Please refer to your Involved Vehicles Listing prior to ordering requirements.

All customers of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors (see copy of customer letter included with this bulletin).

All unsold new vehicles in dealers' possession and subject to this campaign MUST be held and inspected/repaired per the service procedure of this campaign bulletin BEFORE customers take possession of these vehicles.

Dealers are to service all vehicles subject to this campaign at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward.

Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. This could be done by mailing to such customers a copy of the customer letter accompanying this bulletin. Campaign follow-up cards should not be used for this purpose, since the customer may not as yet have received the notification letter.

In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle.

1. Remove the three bolts and the compartment box top.
2. Remove the parking brake reservoir from the pump assembly.
3. Drain the fluid from the reservoir.
4. Clean the reservoir and the pump mating surfaces using residue-free Optikleen Glass Cleaner or the equivalent. Allow to dry completely.
5. Apply a 1.6 mm (1/16 in) to 2.4 mm (3/32 in) bead of RTV Silicone Rubber Sealant, or the equivalent, around the diameter of the reservoir where the O-ring is positioned when installed.

Important: Allow the sealer to cure approximately 20 minutes. If the sealer is allowed to cure too long, it may not seal properly.

6. Using a protected finger, smooth the sealant uniformly around the diameter of the reservoir.
7. While the sealant is curing, loosen the metal pipe at the elbow in the pump inlet and drain the fluid from the pipe. The pipe is routed between the bottom of the solenoid and the pump inlet.
8. Reconnect the pipe.

Tighten
Tighten the pipe nut to 16 N·m (12 lb ft).

9. Loosen the metal pipe at the actuator inlet and at the tee connector.
10. Rotate the pipe and drain it of all fluid. The pipe is routed between the solenoid and the actuator.
11. Reconnect the pipe.

Tighten
Tighten the pipe nut to 16 N·m (12 lb ft).

12. Remove the O-ring located between the pump and the reservoir. Wash the O-ring in hot, soapy water and dry it.
13. Inspect the O-ring. Replace the O-ring if it is damaged.

Important: The locating pin on the reservoir should be in the hole of the adapter ear when properly oriented. The reservoir fill neck orientation should be inboard, toward the frame rail and toward the centre of the component box.

14. Reinstall the O-ring on the pump assembly.
15. Install the reservoir to the pump assembly.
16. Install the reservoir attaching cap screws.

Tighten
Tighten the screws to 6 N·m (50 lb in).

17. If the vehicle is a 1994, 1995 C-Series or is a 1996 C-Series with VIN 1GDG6H1M0TJ514115, 1GDJ6H2J6TJ514132 or 1GDl7H1MTJ514026, proceed to Step 17 as these vehicles do not have the durable solenoid installed.

For all other vehicles, proceed to Step 25 as those vehicles have the durable solenoid.

18. Disconnect the negative battery cable.
19. Disconnect the parking brake solenoid coil electrical connector.
20. Remove the nut and the metal label that is retaining the solenoid coil to the parking brake solenoid valve assembly.
21. Remove the solenoid from the valve assembly and discard it.
22. Install the new 12-volt solenoid coil to the valve assembly.
23. Install the metal label and the coil retaining nut.

Tighten
Tighten the nut to 8 N·m (6 lb ft).

24. Connect the parking brake solenoid coil electrical connector.
25. Connect the negative battery cable.
26. Fill the reservoir between the minimum (MIN) and the maximum (MAX) lines with DEXRON®III transmission fluid.
27. Apply and release the parking brake three or four times to ensure proper operation.
28. Inspect for leaks and correct any leaks as required.
29. Recheck the fluid level in the reservoir and add fluid if necessary.
30. Install the component box top.



31. Using a clean, dry cloth, wipe any dirt, oil, etc., from the upper right hand corner of the component box top. Install the maintenance label.
32. Install the Campaign Identification Label.

Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label". Each label provides a space to include the campaign number and the five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or a ball point pen.

Each "Campaign Identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in by the customer for periodic servicing. Additional Campaign Identification Labels can be obtained from DGN by calling 1-800-668-5539 (Monday-Friday, 8:00 am to 5:00 pm Eastern Standard Time). Ask for Item Number GMP 91 when ordering.

Apply the "Campaign Identification Label" only on a clean, dry surface.

Submit a Product Campaign Claim with the information indicated below.

Refer to the General Motors Claims Processing Manual for details on Product Campaign Claim Submission

Dear General Motors Customer:

Some 1994-1999 GMC C-Series and 1997-1998 T-Series Medium Duty Trucks equipped with the auto-apply park brake and sold for use in Canada may exhibit certain malfunctions that generally may cause the park brake to operate in the as-designed failure mode. These malfunction conditions are as follows:

The first condition can cause an unintended park brake apply at speed. By design, the auto-apply park brake will apply as a fail-safe mode if any power interruption or fluid pressure loss occurs. If this occurred, the Park Brake warning lamp would illuminate, and there would be a noticeable deceleration of the vehicle. There would be no loss of vehicle control and the driver could bring the vehicle to a safe stop at the side of the road. The second condition could cause a slow apply or release of the park brake. The general system requirement for apply or release is 3 to 5 seconds. Longer times (10 seconds) could occur if the reservoir fluid temperature is above 55°C (130°F) or below -18°C (0°F). There is a warning in the Owner's Manual that the driver should not exit the vehicle until the park brake has fully set and the red warning light indicating this has illuminated. Both conditions could cause a failure to release the park brake when the vehicle is parked. Failure to release is a warning feature to prevent damage and should be an indication to the operator to have the vehicle system checked for abnormalities.

As a result of these conditions and their consequences described above, Transport Canada has informed General Motors of Canada Limited that it believes a safety defect exists in these vehicles. General Motors of Canada Limited has agreed to rectify the conditions by conducting a safety campaign.

To help prevent the possibility of these conditions occurring, dealers are to seal the parking brake pump and the reservoir. Some C-Series vehicles are to also have a more durable solenoid installed (T-Series and some C-Series vehicles are already equipped with this solenoid). In addition, included with this letter is an updated maintenance schedule for the solenoid. Please place this insert in the Section titled "Maintenance Schedule" of your Owner's Manual for future reference.

Please contact your GM dealer as soon as possible for details regarding their availability. If parts are not in stock, they can be ordered before scheduling your service date.

This letter identifies your vehicle. Presentation of this letter to your dealer will assist their Service personnel in completing the necessary correction to your vehicle in the shortest possible time.

We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.

Customer Support Department

General Motors of Canada Limited

Enclosure