Rear brakes sticking lightly & Brake light comes on and off - ZR-1 Net Registry Forums

staminqia · 04-13-2021

I have an issue when I drive that the brake light on dash comes on but when I press the brake pedal it goes off and sometimes when stopped and I let off the brake to press the clutch in I Feel the car does not drift back and its held by the brakes.

I took it to a local shop and he said the front brakes are fine and free spinning but the rear wheels have some resistance. He thinks its the HCU Hydraulic control unit HCU and he does not want to touch it. So before I take it to the dealership I wanted to get some insight from the group here to see if my local mechanic is on the right path or there could be another source to the problem?

Thoughts?

TX '90 ZR1 · 04-13-2021

My first thought- Please do not take it to the dealership!!
Hard to diagnose long distance, but my first suspicion would be something going on with the parking/emergency brake.

staminqia · 04-13-2021

Thats what I thought but when I take it for a drive the sticking doesnt happen all the time almost live every second stop light I feel the resistance.

TX '90 ZR1 · 04-13-2021

If the "Brake" light you are referring to is in the instrument cluster and not the ABS warning light I would still suspect adjustment of the parking/emergency brake.
FYI: The brake system is something any competent C4 mechanic should be able to address. Maybe someone can refer you to a good mechanic in your area.

staminqia · 04-13-2021

Yes you are correct, its on the instrument cluster not above the radio cluster. I agree I think my local mechanic doesnt want to deal with it or trouble shoot it.

staminqia · 04-13-2021

TX '90 is there a good video or document that demonstrates how to adjust the parking brake? is at the lever or at the rear caliper?

32valvesftw · 04-13-2021

I had that issue on mine when I first got it. The fluid level was fine the fluid was clean there were no leaks. What ended up fixing it for me was carefully disassembling and repairing the wiring harness to the switch on the master cylinder, I don't think it was making a good connection.

Ccmano · 04-13-2021

Quote:

Originally Posted by TX '90 ZR1

My first thought- Please do not take it to the dealership!!
Hard to diagnose long distance, but my first suspicion would be something going on with the parking/emergency brake.

Absolutely do not take it to a dealership! They will be even more clueless that the guy you brought it too in the first place. They will charge you an arm and a leg for the privilege.

Find a good corvette shop. The system is no different than any other C4 of the vintage.
H

staminqia · 04-13-2021

Quote:

Originally Posted by 32valvesftw

I had that issue on mine when I first got it. The fluid level was fine the fluid was clean there were no leaks. What ended up fixing it for me was carefully disassembling and repairing the wiring harness to the switch on the master cylinder, I don't think it was making a good connection.

What kind of a repair did you do to the wiring harness? were your brakes sticking or just the light came on and off?
any help here would be appreciated.

secondchance · 04-13-2021

?PARK? light indicates parking brake engaged. ?BRAKE? lights up when brake fluid is too low or an issue with brake hydraulics.
If ?BRAKE? light comes on intermittently, I would first check brake fluid level followed by perhaps checking wiring connector to sensor on the brake master cylinder. If both are ok, I would have a competent shop check master cylinder. HCU - hydraulic control unit? Never heard of this.
Rear brake sticking, I think, may be unrelated. Could be floating caliper binding and needing disassembly, clean and lube. Or, parking brake is not releasing fully.
How many miles on the car?

04-13-2021	#1
staminqia Join Date: Dec 2020 Location: Pittsburgh Posts: 145	Rear brakes sticking lightly & Brake light comes on and off I have an issue when I drive that the brake light on dash comes on but when I press the brake pedal it goes off and sometimes when stopped and I let off the brake to press the clutch in I Feel the car does not drift back and its held by the brakes. I took it to a local shop and he said the front brakes are fine and free spinning but the rear wheels have some resistance. He thinks its the HCU Hydraulic control unit HCU and he does not want to touch it. So before I take it to the dealership I wanted to get some insight from the group here to see if my local mechanic is on the right path or there could be another source to the problem? Thoughts?

04-13-2021	#2
TX '90 ZR1 Join Date: Oct 2017 Location: TX Posts: 2,038	Re: Rear brakes sticking lightly & Brake light comes on and off My first thought- Please do not take it to the dealership!! Hard to diagnose long distance, but my first suspicion would be something going on with the parking/emergency brake. __________________ Kenny 1990 #442

04-13-2021	#3
staminqia Join Date: Dec 2020 Location: Pittsburgh Posts: 145	Re: Rear brakes sticking lightly & Brake light comes on and off Thats what I thought but when I take it for a drive the sticking doesnt happen all the time almost live every second stop light I feel the resistance.

04-13-2021	#4
TX '90 ZR1 Join Date: Oct 2017 Location: TX Posts: 2,038	Re: Rear brakes sticking lightly & Brake light comes on and off If the "Brake" light you are referring to is in the instrument cluster and not the ABS warning light I would still suspect adjustment of the parking/emergency brake. FYI: The brake system is something any competent C4 mechanic should be able to address. Maybe someone can refer you to a good mechanic in your area. __________________ Kenny 1990 #442

04-13-2021	#5
staminqia Join Date: Dec 2020 Location: Pittsburgh Posts: 145	Re: Rear brakes sticking lightly & Brake light comes on and off Yes you are correct, its on the instrument cluster not above the radio cluster. I agree I think my local mechanic doesnt want to deal with it or trouble shoot it.

04-13-2021	#7
32valvesftw Join Date: Jun 2015 Location: Texas Posts: 530	Re: Rear brakes sticking lightly & Brake light comes on and off I had that issue on mine when I first got it. The fluid level was fine the fluid was clean there were no leaks. What ended up fixing it for me was carefully disassembling and repairing the wiring harness to the switch on the master cylinder, I don't think it was making a good connection.

04-13-2021	#10
secondchance Join Date: Aug 2006 Location: McLean, VA Posts: 3,723	Re: Rear brakes sticking lightly & Brake light comes on and off ?PARK? light indicates parking brake engaged. ?BRAKE? lights up when brake fluid is too low or an issue with brake hydraulics. If ?BRAKE? light comes on intermittently, I would first check brake fluid level followed by perhaps checking wiring connector to sensor on the brake master cylinder. If both are ok, I would have a competent shop check master cylinder. HCU - hydraulic control unit? Never heard of this. Rear brake sticking, I think, may be unrelated. Could be floating caliper binding and needing disassembly, clean and lube. Or, parking brake is not releasing fully. How many miles on the car?