View Full Version : HELP!! Brakes went out on Highway! 40mph brake pedal to floor!

06-24-11, 01:31 PM
I have a 1993 FWB RWD with 147XXX miles on it. about 2 days agoi was at a stop light the ABS and Traction control light came on and i thought nothing of it...so the light turns green I go and at the next light i try to stop and the BRAKE PEDAL SINKS TO THE FLOOR!! i pump it like a mad man and it still didnt stop. FORTUNATELY i wasnt in a accident. i hit the E Brake and busted a sharp turn.

What could my brake problem be???? Initailly my brakes seemed harder to press than any other car i had owned. I thought it was just the car. in addition about a week and a half ago i started to hear a squeel from the brake area when car was in motion even when brakes were not applied. and a little louder when applied. SOMEBODY HELP! i want to fix this!

Could it be the master cylinder? one of the cylinders at the wheel? brake line? do i need a bleed?? HELP lol i almost died.

ANSWER: brake fluid is at the "min" line. I am not sure wich level it was prior to this. No visable leaks

Sorry for ranting. Thanks in advance :rant2:

06-24-11, 01:51 PM
I'm thinking brake booster.

06-24-11, 02:16 PM
Hmmm...But would a bad Booster cause the brakes to fail completely???? I thought a bad booster would just make the brakes REALLY hard to push. My brake pedal has extended travel and NO BRAKING what-so-ever.

Thanks for the reply

06-24-11, 02:53 PM
The brake booster would not cause any lose of fluid and would not cause the pedal to sink to the floor.

Fill the master cylinder and pump your breaks several times, with the engine running, in park. Then go to the back of the vehicle and and inspect the back of each wheel (you don't need to take the wheels off) with a flashlight. Connecting to the middle of the rear wheels, there should be a brake line; look around that area for wetness. The brake lines cross the rear axle, so look across there for any leaks. If there are no leaks back there, look around under the car for puddles, especially around the frame rails. Finally check the master cylinder and ABS unit for leaks.

I would say that it is more than likely a rear brake line that broke, and not one of the wheel cylinders. There is also a possibility that one of the valves that are connected to the brake line has gone bad and stated leaking.

06-24-11, 03:03 PM
Brake light on? If the rear line went, you would still have front brakes. Maybe it has something to do with the ABS since the lights came on.

06-24-11, 03:28 PM

The ABS and traction control light are off UNTILL i push the brake pedal. once it starts to sink past a certain point those two lights turn on. but they shut off after i turn off the ignition. Any thoughts?

i read in an Edmunds reveiw for the 1993 fwb that the "ABS pump relay" had a nack for going out, but i am unable to find any threads for that. have you ever heard such a thing?

06-24-11, 03:31 PM
I'm not sure if this will help any but through the On board DTC pin -04 (abs and traction control) i get trouble codes 83 and 162

06-24-11, 03:38 PM
162 would be a historical code which would be: 62: Traction disable switch used or RPM signal malfunction

I do not see any code 83 in the ODBI code thread though uner 04. I do see: 73: Spark retard monitoring malfunction
85: Low voltage.

here's the link: http://www.cadillacforums.com/forums/rwd-19xx-1984-deville-fleetwood-1985/114483-obdi-code-reference-thread.html

06-24-11, 04:01 PM
Thanks Outsider

Yea, i was also looking at a list of trouble codes and for pin -04 no 83 was listed.....i thought maybe that list was incorrect. BUT Through the on board controls it shows code 83. i wounder what that could be..

06-24-11, 04:20 PM
Brake light on? If the rear line went, you would still have front brakes. Maybe it has something to do with the ABS since the lights came on.

My '89 Brougham uses the same split braking system and the '93 Fleetwood (it was mandatory after a certain year). I lost all braking effort after the rear brake line blew out; the master cylinder drained and I had no pedal. The front/rear spit is a safety feature designed to bring the car to a stop at very low (parking lot) speeds, and is not intended to effectively slow a car from highway speed.

I'm uncertain of the operation of the ABS light, but on some vehicles, if comes on with the BRAKE warning lamp. The ABS driver (the pump that variates the pressure to the wheels, stopping slip), could also have sensed a lack of pressure and sent up an error code that turned on the ABS lamp

06-24-11, 04:55 PM

yes the red brake warning lamp is on also on. I got under the car as much as i could. i did not see any evident leaking near any of the wheels and it doesnt seem like the Master cylinder reservoir has lost any significant fluid (ive been pumping brakes to see)

06-24-11, 05:56 PM
maybe when the fluid got low some air got in the system? Try bleeding the system and see if that gives you any help.

06-25-11, 09:14 AM
If I'm reading this right, you lost all brakes but the master cylinder still has plenty of fluid in it? It has to be a failed master cylinder. If you blow a rear brake line you will still have some brakes and if the booster quits you should have stiff brakes. Suddenly having no brakes at all is a pretty rare condition

06-25-11, 04:53 PM
Put more brake fluid in it and put your foot on the pedal and look for the leak. It should show up pretty quick and the car doesn't have to be running. If the master cylinder failed the fluid would still go somewhere. If there is something wrong with the brake booster it can also suck in fluid.

The split system is only made to stop the car. You should be able to make a couple normal stops with it but it will still run dry.

Neil Clarke
06-30-11, 06:34 AM
,Master cylinder sounds like the culprit

However.. .the fact you have brake noises also makes me think you better get those wheels off and see if you actually have any pads left
Low fluid level as you describe could be cause your pads,shoes have worn right down

Stop guessing and start looking

07-29-11, 06:42 PM
Hey guys just to let everyone know I fixed the problem. Itwas the Master Cylinder. I bout a new one.....Bech bleed it and threw it on...wah laaa! BRAKES!!! Thanks everyone for the help

05-08-16, 11:33 AM
Same issue with pedal to the floor, still, after replacing the master cylinder twice. Comments below indicate ABS, pump or control valve. Will check it out further this week by disconnecting the ABS.

05-08-16, 12:02 PM
If you live in the north, going to the floor with the pedal, means one things: start looking for a rusted out line.


05-08-16, 12:03 PM
Same issue with pedal to the floor, still, after replacing the master cylinder twice. Comments below indicate ABS, pump or control valve. Will check it out further this week by disconnecting the ABS.

Did you bleed the master cylinder before installing it? Maybe you need to bleed your interest brake system. If you get any air in the lines you will have this problem

Jeff R
05-08-16, 03:07 PM
Probably the master... However now that you jave a known fluid level, keep pumping the brakes. If there is a leak then the fluid level will go down. If one side goes down them you have a leak in that system. If the fluid does not go down then thwre is no leak and you can look elsewhere.