Help Me!BRakes are messed up pedal goes to the floor [Archive] - Forum


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09-11-2012, 04:12 PM
oK I have tried everything. First off its a 99 G/a SE. 3.4L Auto.
the abs light is on. I had autozone check it it says there is no connection from the front sensors. Which is wierd i changed both front wheel bearings already. the sensors are plugged in good. check oohms they all seem to work correctly.( goes down when spinning wheel). I have tried checking where they plug into the abs unit under the batt. tray. its a lil rusted but the connections are good. I have tried bleeding the brakes from the rear right, next rear left, front right then left front. also bled up at the abs unit itself. There is no more air anywhere but i still have no pedal. it will go almost completely to the floor until it actually starts to work. this is crazy:leg
I am at a loss i have no idea where to go next anyone had this prob b4.
also if i pump up the pedal it seems to get a little better but is still almost on the floor till the car begins to stop. With the car off the pedal will get hard. when u turn on the car the pedal will get soft.

09-11-2012, 04:15 PM
there are no external leaks anywhere I tried unplugging the vacuum to the booster and the motor shuts down. so i dont think it is a vacuum problem. I just cant figure this out anyhelp anyone plz!!!!

09-11-2012, 04:45 PM
Had this issue earlier in the year, your master cylinder is bad. Replace it.

As for your ABS light, check the wires for the rear. If that's fine the ABS module itself could be bad, or have bad wiring.

09-11-2012, 06:38 PM
i was thinkin that but the master cyl. is like 100bucks i would hate to change it and it not do anything.

09-11-2012, 07:52 PM
When you press the brake pedal, the rubber seals inside the master cylinder compress the brake fluid which applies the brakes at the wheels.

What sometimes happens is when the internal seals start to wear out, the brake fluid is no longer properly compressed and the pedal goes to the floor because the fluid is getting past the inner seals...this is called internal bypass. One way to tell if this is happening is to remove the master cylinder and check the back side of the plunger area for signs of brake fluid leakage.

The lack of sufficient fluid pressure at the ABS module could be triggering the ABS light, however if the ABS module had a lot of air in it then you might need a Tech II to hold the actuators open while bleeding the brake system. But at this point I agree that the master cylinder is most likely the problem.

09-11-2012, 11:00 PM
Mine went bad due to my own stupidity, I forgot to remove the master cylinder reseviour cap when I did the front brakes last October. Leaving the cap on makes the master cylinder's internal deals more prone to blowing out when the pressure has nowhere to go when you compress the pistons back into the calipers.

09-12-2012, 02:01 PM
i think that very well might have happened to this car to. The actual part where the fluid sits on the master cyl. is a little loose. Like you can rattle it back and forth a little bit its not completly tight against the metal part of the master cyl.
Thanks for the input guys

09-12-2012, 02:02 PM
I did have the master cyl off yesterday. i didn't really notice any fluid behind it but ill pop it off again and check. its pretty easy to pull

09-12-2012, 02:04 PM
I have a 02 impala with the 3.4 L motor in it. would the master cyl be the same as the one on the G/A so i dont' have to buy one just to find out it isn't the problem.

09-12-2012, 03:28 PM
:facepalm: the reseviour is NOT your issue. And no, W-body master cylinders are not interchangeable with the N-body.

Seriously, stop beating around the bush. Replace the master cylinder.

09-13-2012, 03:59 PM
gonna give it a shot friday is payday. I am also tearing down a mazda 626 to replace the head gasket. It was traded in by my moms friend to a chysler dealer and i thought i finally would be rid of the damn lemon. but now the dealer wants me to change the headgasket for them since there mech. doesn't wanna mess with a mazda. Won't that car ever leave me alone. LOL