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Cadillac brake problem


msabot's Avatar
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03-18-03, 02:10 AM   #1  
Cadillac brake problem

Have a 1989 El Dorado w/ ABS brakes. If I come to a normal slow stop, no problem. If I have to react quickly, it feel as if there is a brick under the pedal and the car will not stop! It will slow down and eventually stop but in nowhere near the time or distance it should. On occasion, during these no stopping episodes, one of the tires will lock up and leave a skid mark even though the car is still rolling and my foot is full pressure on the brake pedal. I have other cars with ABS so I know the sensation that your supposed to get when you step on the brakes quickly and this car is nothing like that. Any help will be appreciated.

 
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03-18-03, 03:27 AM   #2  
Joe_F
Likely time for professional service. Don't mess with ABS without the proper tools and knowledge.

 
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03-19-03, 09:57 PM   #3  
This might be a little late but I donít think the problem is ABS related, but I might be wrong. Sound like you could have a clogged line or a booster on itís was out. Either way you will be time and money ahead to take it to a professional.

 
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03-20-03, 05:20 AM   #4  
WeldGod, thanks for the reply. You may have something, as you said to look at a possible booster problem. When the brakes "act-up" it's as if you've lost that vacuum. Something like trying to stop with power brakes and the car not running. This is a last ditch-effort to try fix the brakes or junk the car so I'm trying to avoid taking it to a service center $$$$. I did that once when I first started having the problem but, they couldn't duplicate the condition. Thanks again!

 
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03-20-03, 06:33 AM   #5  
Joe_F
Why would you junk the car? If it's in poor condition all the way around, why throw good money after bad?

 
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03-20-03, 08:22 AM   #6  
Joe,
Thank you for your two helpful replies. They have certainly got me one step closer to solving my problem.

 
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03-20-03, 09:19 AM   #7  
Joe_F
Use autolibrary.org below to study how to test the various components in the braking system. If then, if you don't understand what they have there, it may be time for professional service.

 
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03-20-03, 11:01 PM   #8  
I would start with checking for vacuum leaks, then check for vacuum pressure. You know how to do that right? If all of that checks out I would then suspect your hydraulic assembly. If you front wheel sensor is malfunctioning it could cause that wheel to lock up, or it might no,t that is why ABS is such a pain. Even a corroded wire could cause your brake computer to not get the information it needs. Or you could have a messed up proportioning valve causing wheel lock. I donít know if you car has a front one or not. Just trying to give you options. Some GM brake vacuum check valves get stuck and release vacuum at the most inopportune time. Also your accumulator might be getting low causing the heavy peddle feel. A leaking or partially occluded valve body could cause a heavy feel/ no stop also. Are you getting and ABS light? These cars come with computer diagnosis built in for a reason. And if you unhook a line with ANY pressure in the accumulator you have a 95% chance of doing serious injury to yourself. There are tons of possible combinations of things that could cause your symptoms. If you are not going to take it and get the codes read you really might be messing with problem for a long time to come. You might end up spending a lot of cash for nothing when you do it your self, but if you take it to a shop they should fix the problem the first time. But either way we will help you as much as you can.

 
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03-21-03, 05:12 AM   #9  
This vehicle has no vacuum booster on it.
It uses a hydraulic pump to charge the accumulator.
It is a fully self-contained unit.
You cannot change the master or booster - they are one unit.
You can change the accumulator seperately.
But do not do unless you are ABSOLUTELY sure all pressure is gone.
Sounds like an internal seal failure.
More than likely due to contaminated fluid.
Nobody flushes brake fluid every 2 years like they are supposed to.
You need to do a code check before you go any farther.
These units are not cheap ~ $1800+.
Pull codes and get back to us.

 
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03-21-03, 09:40 AM   #10  
Fishpounder, thanks for your suggestions & warnings.

One of the reasons the service dept. couldn't find the problem is that it's not setting any codes. That was several yrs. ago when it was just doing it occasionally. Now it is constant. I'll double check the codes but it has never set one yet.

 
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