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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3214
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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Its a GMC 1999 c6500. The parking brake pump or motor I

Customer Question

Its a GMC 1999 c6500. The parking brake pump or motor I guess it will not set the brake. And it seems to be running when it should not. I have had it to 2 mechanics so far that cannot fix it
JA: Have your brakes ever been replaced? Have you checked the brake fluid?
Customer: Yes all that was done by both mechanics
JA: What is the model of your '99 GMC?
Customer: c6500. I think its a topkick. The engine is v8 gasoline
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: No I am going to try to get the right part for the mechanic. He says he thinks it is the little relay or solenoid that is mounted next to the pump
JA: The mechanic is ready to answer your vehicle question. Is there anything else you want him to know?
Customer: That the pump was rebuilt and it does function. And there was a time when the brake would not set when the truck was hot but it would set when it cooled down. The problem has been getting the brake to engage, not disengage
Submitted: 7 months ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 7 months ago.

My name is ***** ***** I will assist you with your question today.

I'm an independent contractor and I don't get paid until a rating has been made.

We can go back and forth as needed to help resolve the issue you are having. Follow ups are free after ratings, so rate in confidence!

That motor isn't for the park brake. It is for the regular brakes. When it is buzzing away, there is a malfunction in the flow on the brake system or there is a fault in one of the 2 switches on the pump. There is one located on the brake reservoir and another mounted on the pressure line from the steering pump, mounted on the firewall.

Are you having a park brake issue as well on this? Do you have air park barke valve where there is a yellow knob on the dash or a pull handle park brake where you pull up a big handle to engage the park brake?


You want a 5 star service and I want to provide a 5 star service. Please consider that I don't know your skill level as well as I can't see, touch, smell, hear the vehicle/machine in question. Please provide as much detail as possible and I will provide as much back.

Once an answer is provided, you should see a rating screen. Please rate my personal service to you. The ratings are my personal feedback, they are not the site feedback.

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Customer: replied 7 months ago.
Yellow knob on dash
Expert:  Jeremy replied 7 months ago.

That yellow knob doesn't run on the motor. It uses a different brake system. Your mechanics are getting the systems backwards.

Expert:  Jeremy replied 6 months ago.

I see you viewed this with no response or positive rating given, therefore the question is still showing as an open question.

Did you still need assistance? Were you able to understand the information I provided above? If you need help, I'm willing to assist more. I just don't want the question to time out due to no reply when help is still needed. If no help is needed, you can reply that as well that you are satisfied with the response and I can then know that this question is resolved for right now.


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