m0sh_man Posted December 3, 2003 Report Share Posted December 3, 2003 When i hit the brakes on my 91GTP the dash brake light comes on, then i hear this tiny grinding noise from under the dash and the pedal gets much firmer, then the light goes off, it does this everytime i hit the brakes, and when the light goes off i feel the car start to stop much faster, the thing under the dash that makes the grinding noise has to be the power brake system or something, but im not sure, maybe the ABS? id like to get this fixed. BTW my car is a 5 speed if it makes any difference. matthew Quote Link to comment Share on other sites More sharing options...
Cheesy411 Posted December 3, 2003 Report Share Posted December 3, 2003 Mine did that on my 94 cutlass supreme the result was low brake fluid and rusted to shit lines maybe that could be it :? :? Quote Link to comment Share on other sites More sharing options...
m0sh_man Posted December 3, 2003 Author Report Share Posted December 3, 2003 the only place this car has any rust is on the battery tray which i think resulted because of a battery explosion sometime in its life. the fluid isnt low at all. any clue what makes the noise under the dash? matthew Quote Link to comment Share on other sites More sharing options...
ismellrealbad Posted December 3, 2003 Report Share Posted December 3, 2003 the grinding noise under the dash almost sounds like the ABS self test that happens when u start the car. do you start the car with your foot on the brake? if you do it wont self test on startup and you wont have abs. well mine does it as soon as i take my foot off but maybe urs is acting erratic? can you take a recording of the sound? Quote Link to comment Share on other sites More sharing options...
quaddriver Posted December 3, 2003 Report Share Posted December 3, 2003 The 'grinding noise' sounds like the old Kelsey hayes 4wABS gm used to use....and the pedal kinda vibrates with it? why it would be triggering everytime you hit your brakes will require some diagnostic work with a scan tool. Quote Link to comment Share on other sites More sharing options...
m0sh_man Posted December 3, 2003 Author Report Share Posted December 3, 2003 the grinding noise happens everytime i hit the pedal, if i push the brake and hold it in, i hear the grinding noise, the pedal gets real stiff, then the noise goes away, (all with my foot held firmly on the brake) now as i have the brake pushed, the brake light comes on, once the grinding noise stops, the light goes off. it almost sounds like a little electric motor in there stiffening up my brakes. matthew Quote Link to comment Share on other sites More sharing options...
no1kicker Posted December 4, 2003 Report Share Posted December 4, 2003 that's the pump running for the brakes. The red brake light means low pressure in the system, hence why the pump has to run. Quote Link to comment Share on other sites More sharing options...
m0sh_man Posted December 4, 2003 Author Report Share Posted December 4, 2003 that's the pump running for the brakes. The red brake light means low pressure in the system, hence why the pump has to run.[/quote so how do i get the pressure UP in the system? it has plenty of fluid in the resevior and it also has been bled several times, now when i open up the bleeder valves fluid comes dripping out fast very very steady pace. matthew] Quote Link to comment Share on other sites More sharing options...
quaddriver Posted December 4, 2003 Report Share Posted December 4, 2003 that's the pump running for the brakes. The red brake light means low pressure in the system, hence why the pump has to run.[/quote so how do i get the pressure UP in the system? it has plenty of fluid in the resevior and it also has been bled several times, now when i open up the bleeder valves fluid comes dripping out fast very very steady pace. matthew] aha.....did you change something on the brake system where an air bubble may have travelled back to the abs unit? very common ugly with that system, a bi-directional scan tool with ABS ability has to be used to signal the abs unit to cycle the individual pumps to open, while the unit itself is bled off Quote Link to comment Share on other sites More sharing options...
no1kicker Posted December 4, 2003 Report Share Posted December 4, 2003 how old is the accumulator? That is what supplies the pressure. Quote Link to comment Share on other sites More sharing options...
m0sh_man Posted December 5, 2003 Author Report Share Posted December 5, 2003 so whats the accumulator? matthew Quote Link to comment Share on other sites More sharing options...
no1kicker Posted December 5, 2003 Report Share Posted December 5, 2003 little black ball to the left of the master cylinder. go to turbogpgarage.com there's some good info on the site. Quote Link to comment Share on other sites More sharing options...
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