Hot Rod Forum banner

Hydro-boost system... brake light on...

7K views 5 replies 5 participants last post by  ViperMonster800 
#1 ·
My beautiful 1985 Chevy Caprice wagon has hydro-boost. Brake fluid is topped off but brake light remains on. I pump the brakes when the light is on and it turns off once in a while and restores power.

When I'm coming to a stop, I press on the brake once for a second and then let go and press it again and it keeps the brake light from coming on and losing the booster power.

Any idea whats causing this?
 
#2 ·
My guess is that the master cylinder might be due for replacement, or the rear shoes may be badly out of adjustment.

Does either side of it (front or rear) seem to be needing top-ups?

If you're capable of doing so yourself:
1.) Check for leaks ... everywhere.
2.) Remove rear drums, inspect wheel cylinders and friction material, adjust rear shoes.
3.) Bleed the brake lines at all four corners.

If you don't feel confident at all in your ability, or if these problems persist ... get it fixed by a pro.

Brakes are important.
 
#4 ·
matt167 said:
your loosing 1 side of your brake lines intermittantly ( probably shoes too far out ) causing the brake light to go out. GM brake light switches are self centering, that's why it'll go out.
thats what caused my light to do the same with hydraboost, was the rear brakes not working. proportioning valve is pushed off center when one brake is doing all the work. Ed ke6bnl
 
#5 ·
Not hydroboost - Power Master

I don't think you have hydro-boost, I think you have the Power Master system with the integral electric pump. Hydroboost usually refers to the system used on trucks and diesels where the hydraulic brake booster is pressurized from the power steering pump. The Power Master has a small electric motor and pump hanging under the master cylinder that supplies pressurized fluid to the booster. A ball-shaped accumulator stores the hydraulic pressure until you press on the brake pedal. There's a pressure switch that turns the pump off and on as necessary to maintain the correct pressure in the accumulator.

There are several reasons why the brake light goes on. As others have noted, it could be due to leakage problems in the actual brake hydraulics. The Power Master also will trigger the brake warning light if you have problems with the pump or if the accumulator doesn't maintain pressure. Accumulator failure is a common source of problems with this system. Finally, check for a corroded connector on the motor. My friend's Buick GN recently had this problem.
 
#6 ·
I've replaced the rear brake shoes, drums and hardware... including the wheel cylinders. It very well could be the rear brakes... the reason is BEFORE I did the rear brakes, I adjusted the emergency brake cable to actually grab the drum. After I did the rear brakes, the rear drums were ever so tight and I never loosened the emergency brake cable to the factory setting. Therefore causing me to wear out my rear brakes quicker. Am I on the right track?

I know, not the brightest thing in my book. Thank you for your input yall, its given me a new perspective. :thumbup:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top