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Cadillac DeVille ABS And Brake Light On

Q. Hi Vincent, I spoke to you a ways back, concerning the improperly set TPS and ISC as placed on my 1987 Cadillac DeVille. Your advice worked wonders. I thank you for taking the time to read this. Now, I have what will most likely be a very expensive dilemma. The amber "ABS light" illuminates permanently on the information window, and the red "Brake" lights blinks intermittently most of the time.

Cadillac DeVille ABS And Brake Light On

My brake pedal feels normal, although you can feel a heavy "vibration" in the pedal, correlating the sound of what I believe is the "hydraulic" ABS pump. You can really hear the pump trying to work, or at least a heavy "buzzing" coming from the master cylinder area.

I have NO brakes, it appears that the only braking on this car is when you press the brake pedal, ignore the pedal vibrations and the car attempts a ridiculous braking distance and barely stops. It's as if the calipers are not grabbing the discs, or only a very light pressure is applied.

The brake fluid level is full, I make sure I depress the brake about 25 times before I check it. The pads, rotors, and drum brakes are all new and readjusted.

I even tested the brake vacuum reserve by depressing the pedal the same way, and turning the key to "ON". You can feel the power booster "dropping" the pedal just a bit as normal. If you can, give me the good, or BAD news.

I know this car had a recall for the ABS relay and the hydraulic pump when it rolled off the assembly line. I imagine after 17 years, it will need some new parts. I have now deemed the car "undriveable" as it now sits nestled under a parking lot awning.

One final note, is it possible for me, I know there are safety concerns, to find some of the more expensive ABS/component parts from a salvage yard? I realize the reliability concerns.

Thanks,
Paul

A. The first thing I would do is contact a Cadillac Dealer and find out if the recalls were done. If not, then I would recommend having them done as soon as possible.

If it was done, then the most likely problem is a bad pump motor relay. The pump motor relay contacts may become welded together causing the pump motor to continue running after the specified system pressure is attained. This leads to the pump motor burning out.

If this is the case, make sure you use a GM pump motor relay, part number 25525848, when you replace the pump motor. When the pump motor goes bad, you lose rear brakes and have very little pressure application to the front brakes.

From the recall bulletin:

The Antilock Brake System (ABS) pressure/warning switch may exhibit brake fluid seepage which eventually can lead to loss of the brake system hydraulic pump motor. Additionally, the hydraulic pump motor and ABS electrical relays may have been exposed to water contamination during vehicle assembly.

This condition can cause loss of the hydraulic pump motor and/or loss of the ABS function. Loss of the hydraulic pump motor would result in a total loss of rear brakes as well as power assist to the front brakes. The red brake warning light would illuminate and stay on.

If this warning is not heeded, a loss of rear brakes at a time when minimum stopping distance is required could result in a vehicle crash. An inoperative ABS electrical relay could cause loss of the ABS function, but normal power assisted braking would be retained.

The amber ABS warning light would illuminate and stay on. The ABS and hydraulic pump motor electrical relays and 30 amp fuses will be replaced. In addition, the hydraulic pump motor assembly and pressure/warning switch will be inspected and, if required, replaced.

As for using junk yard ABS parts, if you are going to put your wife and children in the car, which parts do you think they deserve? New from the dealer, or a part that's been sitting in a junk yard for who knows how long?

On a personal note, has any of the Wells Fargo Stage Coaches been robbed lately? I just want to make sure my money is safe.

Additional Information provided courtesy of AllDATA

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