moparman

Car is '96 Firebird Formula. Brake pedal goes to the floor. Master cylinder is full. Brake light doesn't come on. No obvious leaks or loose brake lines. Brakes were working fine one day, the next not at all. What are things to look for?

JakeRobb

Start the engine. Drive the car to somwhere you candeal with some leaking brake fluid. Keep it running and pump the pedal all the way down and back up like fifty times. Get out and check the master cylinder. If the fluid level has changed, look underneath — this should be enough to reveal even the non-obvious kind of leak.

If there are no leaks, then you have air in the lines somewhere. Bleed the whole system with fresh fluid.

Injuneer

The fact the "BRAKE" light has not turned on would seem to be indicating there is no difference in pressure between the front and rear brake hydraulic circuits. Would indicate both systems are leaking (unlikely), or the master cylinder has somehow become unable to pressure both front and rear systems.

moparman

I'm beginning to suspect the master cylinder. I had to send the car to a shop. I fooled around with it for a couple of hours, but we have snow and ice, and I don't have a garage. Almost froze and finally had to give up. The shop has found no leaks.

Do these cars have an ABS module, and would a failing one cause no brakes?

DrewHMS97SS

As far as I know, failing ABS just causes that portion of the system not to function. The ABS pump is on the front driver side of the engine well, where the lines from the master cylinder connect. I had my ABS light on and not functioning because of melted wires to the front speed sensors, but normal brake operation still functioned.

Injuneer

The EBCM (Electronic Brake Control Module) is on the drivers side, above the side kick panel. At least on a 94. Not sure what year your car is. For 94/95, codes can be read with Scan9495. Some, but not all of the codes will turn on the "BRAKE" light.

I can't conceive of any module failure that would result in the pedal going all the way to the floor, with no resistance.

moparman

Just got the car back from the shop. The front caliper slide pins were rusted, especially the right front, so bad the calipers wouldn't work. They cleaned things up, used the proper grease on them, and bled the brakes. They work fine now.

DrewHMS97SS

It had to also be air in the lines. If the calipers couldnt move, you shouldn't have been able to floor the pedal. Glad that your brakes work now!

moparman

Forgot to mention air was found in the right front caliper. Bleeder on right front was rusted up and had to be replaced. Guess air could have got in through there some way.