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1999 Seville SLS brake problem


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Hi all.

We have a problem with our 1999 Cadillac Seville SLS whereby every now and then when you apply the brake, especially just after leaving the driveway but it has done it other times too, there is no brakes. There appears to be pedal pressure as in the pedal does not go to the floor, but they just do nothing. This only happens one time out of about a hundred but when it does it, it's scary. The rest of the time the brakes are fine.

What could this be?

Thanks in advance.

Glenn.

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welcome to caddyinfo.

A few questions.

When the brakes fail does the pedal drop low?

Does it seem to fight when you press harder on the pedal?

I am curious if this could be ABS related. If it is it could be a failure of a hub assembly and it is seeing a lockup and releasing the brakes

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I have 2000 sts and have experienced the same problem, intermittent and mostly only at firststart up, thank goodness.I was full of fear knowing how expensive abs parts are,we have no wreckers with these cars in austra;lia!! Might be 50 of these cars here.Anyhow, there is a relay that controls abs motor and that was my problem .It has 2 pink wires , ablue and a red ,and on my car sits behind the abs on the strut tower..Mine is right hand drive so not sure of your position .Handbook is not clear on this or I cant find it. Took a bit of isolating as it was the last thing I expected. Hope this helps you too.Also the earth for these modules is G110 down on the front at the bottom of the radiator.I have solved a good few problems over the years by paying attention to these earths. good luck this is a great practical forum, though I am a bit of a lurker! trevor.

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very useful post. Iam having abs pump issues with my 01 eldo. I want to check the grounds out, also have been looking for the relay info. I want to cycle the pump manually to run it.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 3 weeks later...

When was the brake fluid last changed?

Not sure when the brake fluid was last changed but if it was something like the brake fluid then wouldn't it do this all the time and not just once every now and then?

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I have 2000 sts and have experienced the same problem, intermittent and mostly only at firststart up, thank goodness.I was full of fear knowing how expensive abs parts are,we have no wreckers with these cars in austra;lia!! Might be 50 of these cars here.Anyhow, there is a relay that controls abs motor and that was my problem .It has 2 pink wires , ablue and a red ,and on my car sits behind the abs on the strut tower..Mine is right hand drive so not sure of your position .Handbook is not clear on this or I cant find it. Took a bit of isolating as it was the last thing I expected. Hope this helps you too.Also the earth for these modules is G110 down on the front at the bottom of the radiator.I have solved a good few problems over the years by paying attention to these earths. good luck this is a great practical forum, though I am a bit of a lurker! trevor.

So are you saying that your ABS motor control relay was bad and that you replaced it or are you saying that the earth for the module was the fault? How do you test to determine what the fault is? What is G110 referring to? Excuse my ignorance. I have done some major operations on this Cad such as removing the entire interior and dash in order to replace a leaking heater core, but working on ABS brakes is news to me.

Our Cadillac is right hand drive too by the way, but still built in Detroit.

There are no companies here that specialize in working on these late 90's Cads and anyone you take it to will spend your hard earned money with trial and error diagnoses at $120 an hour until they replace enough parts they hit the jackpot in solving the problem, but rack up charges of $3000 in the process, which we don't want.

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welcome to caddyinfo.

A few questions.

When the brakes fail does the pedal drop low?

Does it seem to fight when you press harder on the pedal?

I am curious if this could be ABS related. If it is it could be a failure of a hub assembly and it is seeing a lockup and releasing the brakes

When the brake fails, the pedal is at the same position at the floor, offering firm resistance as if the brake fluid is being pumped, but nothing happens at the wheels.

Not sure what you mean by does it seem to fight...?

It is unusual that for me at least, it has only ever done this in the driveway and the brakes while driving are fine though a little spongy.

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under normal braking the pedal should not go to the floor, you Are saying that when this happens it does?

ABS brakes are not meant to be pumped. just to be clear.

When this occurs does the pedal seem to push back up as you push harder? Thus the abs releasing pressure

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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under normal braking the pedal should not go to the floor, you Are saying that when this happens it does?

ABS brakes are not meant to be pumped. just to be clear.

When this occurs does the pedal seem to push back up as you push harder? Thus the abs releasing pressure

No the pedal does not go to the floor, it goes to the same level from the floor that it does under normal braking. No I am not pumping the brakes. No the pedal does not seem to push back up.

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Ok thanks. This is deifnately weird. Something must be causing this. I would say a hydraulic problem would not come and go like this, and if it was abs related you should hear the pump. Maybe there is something else you can notice when it occurs.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Wasnt there a discussion a few years back about o rings in the abs unit swelling up causing such symptoms? Also if unsure how old the brake fluid is, i would change it out. New fresh fluid just might remedy a sticky valve or seal in the system.

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I have personally never run into a problem like this. doesnt mean it doesnt happen though. I have dealt with the kelsey hayes, bosch, and other abs units and the main problems I have seen are electrical problems, pump motor, corrosion in the BPMV, etc... but usually none of these affects normal operation

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 2 weeks later...

Fury sorry i havent replied to your question, been out of town.In my case this was simply the relay failing intermittently.Get another one and try it.Can you see this particular relay?

Different circuits on this car use earths in various places.That particular earth is the g110 I was referring to, and is on the left of the motor at the front right down low You cant really see it untill you take the water reservoir off.They are fairly critical on these cars,ive found

.Didnt get where you are living with a right hand drive car. Like you there is only 1 mechanic with a cadillac analysis tech 2 tool in the whole of our city of 4 million!! Guess what he charges??

Thats all about to change .Our gm holden manufacturing plants are all closing, case of union domination here and they dont rea;lize they lost.Cadillac says they will be here within the next 3 to 4 years.Hows that!! Im off topic sorry must start another thread, Trevor

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Fury sorry i havent replied to your question, been out of town.In my case this was simply the relay failing intermittently.Get another one and try it.Can you see this particular relay?

Different circuits on this car use earths in various places.That particular earth is the g110 I was referring to, and is on the left of the motor at the front right down low You cant really see it untill you take the water reservoir off.They are fairly critical on these cars,ive found

.Didnt get where you are living with a right hand drive car. Like you there is only 1 mechanic with a cadillac analysis tech 2 tool in the whole of our city of 4 million!! Guess what he charges??

Thats all about to change .Our gm holden manufacturing plants are all closing, case of union domination here and they dont rea;lize they lost.Cadillac says they will be here within the next 3 to 4 years.Hows that!! Im off topic sorry must start another thread, Trevor

Trevor. For the record I am in Auckland, New Zealand. There are only 4 million people in our whole country but there would be at least 100 of these model Cads in Auckland alone.

I doubt a scan tool will throw any light on this problem because it is too intermittent, and besides there are no error codes being illuminated.

OK I am confused. First you talk about a relay and then you talk about this being an earth. Do you mean the earth for the relay?

I know where you describe on the left of the motor at the front down low there is an ABS module. Is that what you mean.?

Cheers.

Glenn.

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sorry mate, youre right, my car never threw any codes either, and I wasnt as clear as I should have been.Yes the earth for this relay circuit is the one I was referring to .The relay itself should be in the same place as mine -that is attached to the top of the strut tower.All the later g m holden commodores have a small poled relay you could probably get over there to replace it with.I have my car and one other that both had this fault happening. trevor.

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sorry mate, youre right, my car never threw any codes either, and I wasnt as clear as I should have been.Yes the earth for this relay circuit is the one I was referring to .The relay itself should be in the same place as mine -that is attached to the top of the strut tower.All the later g m holden commodores have a small poled relay you could probably get over there to replace it with.I have my car and one other that both had this fault happening. trevor.

Hi Trevor.

I have access to a 1999 Seville wreck which has most of the parts still on it. We bought it a few months ago. The guy who sold it to us paid $20,000 for this car, drove it a couple of years then lost the keys. He got another key and the agent here programmed it incorrectly...so he gave up!!!! He dreamed of having a glass coffee table with a V8 for a base, so he stripped the car to get the block out. We got everything else. What a ridiculous waste of a good driving car!! His loss our gain.

Anyway, photo attached of this wreck. Can you see the part you are referring to in the photo? All the removed parts we have are in the trunk. I hope I can attach the photo successfully I have not done this before on this site...

Glenn.

http://s587.photobucket.com/user/57FURY/media/IMG_5632.jpg.html

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