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Unread 10-10-2009, 02:00 PM   #1
WILLTAKE
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Brake issues on GMC Topkick

Okay, I know that it is not a Jeep and not a common tow rig but I need some help.

The truck is a 1995 GMC Topkick with a CAT 3116 engine and an automatic transmission. It is a 25950 GVW with hydroelctric(?) brakes. There is a brake control box mounted on the kick plate in the driver side area.

The premise of this system is that when the vehicle is placed in park the parking brake engages and when taken out of park the parking brake disengages. There is also a brake control on the dash that ties into the system.

The problem: when the truck runs for a long time unloaded or moderate hauls loaded the parking brake system stops working correctly. Either the parking brake will not engage or will not disengage. To add to that on the control box it shows a digital readout 00 when in park 99 when in gear. As the truck gets hotter the read out will sometimes drop to 60 while driving which makes me parking brake light on the dash flash. I do not want to take a chance with the brakes locking at highway speeds. Also when the parking brakes do act up the control on the dash is no longer effective. If the truck is turned off and allowed to cool down the problem goes away.

I know that there was a recall in later year Topkick for a pressure switch and that has already been replaced.

Any suggestions?

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Unread 10-10-2009, 04:04 PM   #2
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Quote:
Originally Posted by WILLTAKE View Post
Okay, I know that it is not a Jeep and not a common tow rig but I need some help.

The truck is a 1995 GMC Topkick with a CAT 3116 engine and an automatic transmission. It is a 25950 GVW with hydroelctric(?) brakes. There is a brake control box mounted on the kick plate in the driver side area.

The premise of this system is that when the vehicle is placed in park the parking brake engages and when taken out of park the parking brake disengages. There is also a brake control on the dash that ties into the system.

The problem: when the truck runs for a long time unloaded or moderate hauls loaded the parking brake system stops working correctly. Either the parking brake will not engage or will not disengage. To add to that on the control box it shows a digital readout 00 when in park 99 when in gear. As the truck gets hotter the read out will sometimes drop to 60 while driving which makes me parking brake light on the dash flash. I do not want to take a chance with the brakes locking at highway speeds. Also when the parking brakes do act up the control on the dash is no longer effective. If the truck is turned off and allowed to cool down the problem goes away.

I know that there was a recall in later year Topkick for a pressure switch and that has already been replaced.

Any suggestions?
Maybe just replace whatever module it is on the kick panel that controls all of this?
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Unread 10-10-2009, 05:21 PM   #3
WILLTAKE
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I should also mention that I have had this at my mechanic's shop a few times and he has had no luck figuring it out either. He is a Nissan UD shop and GM certified mechanic and can't access the GM medium truck duty books through his account.

If I knew for sure that the box on the kick plate would fix it I would try but everything on that truck is BIG BUCKS to replace. The pressure switch was 250 itself and that is the cheapest piece in the system.

Thanks for the suggestion- If I have no luck I just may end up replacing it anyway
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Unread 11-03-2009, 06:37 AM   #4
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THE READINGD YOU SEE ON THE BLACK BOX ON THE FLOOR ON THE D/S IS THE PREASURE READINGS FOR THE PARKING BRAKE SYSTEM. THERE IS A PREASURE SWITCH MOUNTED TO THE PUMP UNDER THE STEP ON THE D/S , ALSO FLUID IN PUMP EASILY BECOMES CONTAMINATED WITH WATER CAUSING PREASURE PROBLEMS. FLUSH SYSTEM OUT AND REFILL WITH TRANS FLUID, THERE IS ALSO A SOLENOID BY THE PUMP THAT WHEN HOT WILL CAUSE THE BRAKE TO APPLY.HERE IS THE TSB FOR THE TRUCK.

00005: Product Safety - Auto-Apply Park Brake Performance - (Oct 18, 2000)


Subject: 00005 -- Auto-Apply Park Brake Performance


Models: 1994-1999 GMC C-Series Medium Duty Trucks

1997-1998 GMC T-Series Medium Duty Trucks




--------------------------------------------------------------------------------
Condition
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:

• An interruption of electrical power to the hydraulic pump due to a solenoid failure, or

• Water contamination of the DEXRON®III transmission fluid in the reservoir due to inadequate sealing.

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).

Vehicles Involved
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:

Year
Division
Model
Plant
From
Through

1994
GMC
C
Janesville
RJ502453
RJ524067

1995
GMC
C
Janesville
SJ500065
SJ526782

1996
GMC
C
Janesville
TJ500058
TJ517676

1997
GMC
C
Janesville
VJ500135
VJ514306

1998
GMC
C
Janesville
WJ500495
WJ512237

1999
GMC
C
Janesville
XJ506117
XJ519910

1997
GMC
T
Janesville
VJ506117
VJ510922

1998
GMC
T
Janesville
WJ500774
WJ503258

Important: Dealers should confirm vehicle eligibility through GM Access or VIN listing prior to beginning campaign repairs. (Not all vehicles within the above breakpoints may be involved.) Only affected VINs will be paid.


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 Information
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.

Part Number
Description
Qty/ Vehicle

12388081
Solenoid Coil
1 (C-Series Only)

00993033
Optikleen Glass Cleaner
500 ml

12346286
RTV Silicone Rubber Sealant
1*

15156687
O-Ring Seal
1 (If Required)

10952624
DEXRON®III Trans Fluid
1 L

15753013
Maintenance Label
1

* -- One tube will service two vehicles.

Customer Notification
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).

Dealer Campaign Responsibility
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.

Service Procedure
•Remove the three bolts and the compartment box top.
•Remove the parking brake reservoir from the pump assembly.
•Drain the fluid from the reservoir.
•Clean the reservoir and the pump mating surfaces using residue-free Optikleen Glass Cleaner or the equivalent. Allow to dry completely.
•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.

•Using a protected finger, smooth the sealant uniformly around the diameter of the reservoir.
•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.
•Reconnect the pipe.
Tighten
Tighten the pipe nut to 16 N·m (12 lb ft).

•Loosen the metal pipe at the actuator inlet and at the tee connector.
•Rotate the pipe and drain it of all fluid. The pipe is routed between the solenoid and the actuator.
•Reconnect the pipe.
Tighten
Tighten the pipe nut to 16 N·m (12 lb ft).

•Remove the O-ring located between the pump and the reservoir. Wash the O-ring in hot, soapy water and dry it.
•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.

•Reinstall the O-ring on the pump assembly.
•Install the reservoir to the pump assembly.
•Install the reservoir attaching cap screws.
Tighten
Tighten the screws to 6 N·m (50 lb in).

•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.

•Disconnect the negative battery cable.
•Disconnect the parking brake solenoid coil electrical connector.
•Remove the nut and the metal label that is retaining the solenoid coil to the parking brake solenoid valve assembly.
•Remove the solenoid from the valve assembly and discard it.
•Install the new 12-volt solenoid coil to the valve assembly.
•Install the metal label and the coil retaining nut.
Tighten
Tighten the nut to 8 N·m (6 lb ft).

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




•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.
•Install the Campaign Identification Label.
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.

Claim Information
Submit a Product Campaign Claim with the information indicated below.

Repair Performed
Part Count
Part No.
Parts Allow
CC-FC
Labour Op
Labor Hours*
Net Item

Seal Parking Brake Pump & Reservoir; Install Maintenance Label
0 or 1
--
**
MA-96
V0461
0.5 hr
***

Seal Parking Brake Pump & Reservoir and Install New Solenoid Coil & Maintenance Label
1 or 2
--
**
MA-96
V0462
0.7 hr
***

* -- For Campaign Administrative Allowance, add 0.1 hours to the "Labour Hours".

** -- The "Parts Allowance" should be the sum total of the current GMSPO Dealer Net price plus 40% for parts needed to complete the repair.

*** -- The amount identified in the "Net Item" column should represent the sum total of the Current GMSPO Dealer Net Price plus 40% for the actual amount of cleaner, sealant, and transmission fluid needed to perform the required repairs, not to exceed $20.00


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

Owner Manual Insert





February, 2000
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:

• An interruption of electrical power to the hydraulic pump due to a solenoid failure, or

• Water contamination of the DEXRON®III transmission fluid in the reservoir due to inadequate sealing.

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

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY
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Unread 11-04-2009, 01:36 AM   #5
WILLTAKE
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THANK YOU!!! This is exactly what I needed. My VIN falls right in the middle of the group for 95 and the symptoms are dead on. This looks much better than replacing the electronics.
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