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Tim West
Tim West, ASE Certified Technician
Category: Car
Satisfied Customers: 4638
Experience:  ASE Certified Service Manager for Bridgstone/ Firestone
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1992 oldsmobile regency: some strange symptoms with the brakes

Customer Question

i own a 1992 oldsmobile regency elite. i am having some strange symptoms with the brakes. they will sometimes go completely dead when trying to stop. (straight to the floor with no resistance.) then the problem will just go away again. as far as i can tell there is no pattern to this. there are never any warning lights on the dashboard. i have changed out the master cylinder, none of the lines are damaged or leaking, and the brake pads are fine. i don't think there is any air in the system. i am very stumped by this.
Submitted: 8 years ago.
Category: Car
Expert:  Tim West replied 8 years ago.
Thans for choosing JA

The vehicle has a Pressure Modulator Valve.

Scan the modules for codes...

You can b ypass the Pressure Modulator Valve (PMV) with fittings.

Bleed the brake system.
Road test and evaluate the brake pedal.

If problem seems solved, replace the PMV.
Customer: replied 8 years ago.
There are no warning lights on the ABS system and the problem is intermitant. Is that still likely to be the PMV?
Expert:  Tim West replied 8 years ago.

Electrically disconnect brake pressure modulator valve, system should revert to base brake system.
Possible the caliper pistons were pressed while bleeder screws were closed, fluid and pressure will cause bpmv valve(s) to stick.

Now the problem is going to be the brake modulator, however It would not be a bad idea to recheck the whole braking system.