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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 1999 chev C6500 I cannot get the parking brake to

Customer Question

I have a 1999 chev C6500 I cannot get the parking brake to release.the solenoid was shorted,causing the circuit breaker to trip.I replaced the solenoid.Now,when i push the button in to relaese the brake,the pump runs like it should,but i dont understand what makes that actuator release,it only has one line to it,so does it actuate first,then relase pressure through the solenoid valve?I just dont quite understand it.
Submitted: 6 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 6 years ago.

Welcome, and thanks for using Just Answer. I am Cam, and I will do my best to assist you. When you are finished please click on accept only if you are satisfied. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can. About your vehicle,

Push in on the parking brake switch in order to release the parking brake. The parking brake control module (PBCM) turns on the pump motor in order to supply fluid pressure to the actuator. There is a large spring inside of the actuator that applies the parking brake. The piston moves in the actuator when the fluid pressure overcomes the spring tension. This movement transfers to the parking brake through the parking brake cable. The pump shuts off and the PBCM monitors the system pressure when the parking brake is released. The PBCM turns on the pump in order to build pressure if the pressure drops too low.

Pulling out on the parking brake switch de-energizes the parking brake solenoid in order to dump the fluid into the reservoir. The spring in the actuator moves the piston and applies the parking brake through the movement of the parking brake cable as the pressure decreases.