NEED hydroboost brakes

Moshman1205

Registered User
i have a 91 s.c. and the hydroboost brakes are faling. the pump in it runs continuously and killed my car. it doesnt build up pressure for brakes to work. so im assuming im going to need the entire booster. so if anyone knows where i can get one or has one that would be great. if it must be delivered id like to do paypal or c.o.d. this way no one gets messed over. thanks guys. Devin.
 
Several things can cause the pump motor to run all the time....

Most likely the pressure switch not cutting power to the pump....

Are you getting and dash lights (red brake and amber ABS lights).....

What do you mean when you say it "killed your car"....
 
If it ran all day, even with the key turned off, then I think the ABS relay is stuck and needs to be replaced.
 
If it ran all day, even with the key turned off, then I think the ABS relay is stuck and needs to be replaced.

I would check the brown ABS relay first as it is the easiest part to get to.....:p

Pull it out and apply voltage to the two small terminals.....

If it is good, you will hear and feel it click....

You said the accumulator was hot.....

Do you have enough brake fluid in the reservoir....:confused:

Your accumulator could be bad....
 
For the ABS pump to run all the time, and with the key out, it is likely the pressure switch has failed, and the power relay for the brakes has failed. The high temperature of the fluid will be from the high heat generated from the pump running all the time.

A good resource for the braking system on your car is at the 35th Anniversary site.http://www.35thatr.org/Tips/ABS.htm has a description of how to trouble shoot the system with wiring diagrams and testing ideas.
 
Awesome info guys thank you, this is frustrating to say the least. Also. Where would the brown? ABS relay be located at?
 
Ok so according to this website the accumulator is bad. When reassembling the system I checked the little hose to make sure it was free of anything. But for it Eton run when the key is off? And for so long to kill the battery? It should have "overheated" and shut off. There is plenty of fluid in it
 
Ok so according to this website the accumulator is bad. When reassembling the system I checked the little hose to make sure it was free of anything. But for it Eton run when the key is off? And for so long to kill the battery? It should have "overheated" and shut off. There is plenty of fluid in it

I think you may be quoting the website out of context. I mean, maybe the accumulator is bad. But the pump should never run when the key is off. You have to check the control side of the system.

I am not sure if you can unplug the pressure switch connector to isolate the relay part of the system and test for the fault there. Maybe Big E knows. But the relay is not that hard to get to anyway. It's on the firewall, near the passenger side shock tower. The only thing you might need to remove to get it out is the BAP sensor, which just has 2 screws, and the cowl weatherstrip.
 
The brown ABS relay is located on the firewall, under the windshield cowling, near the passenger side hood strut....

It can be a pain to get to as it is tucked in there pretty good.....:rolleyes:

You might have better luck removing the holder that it sits in to get better access to it.....

Once you have it out, do like I said in my previous post to test it....

If it turns out to be bad, you can still get them at the parts store or I have quite a few of them.....:p
 
You should start a thread in the tech forum.

From this statement
the pump in it runs continuously and killed my car.

It seems you have more problems than possibly a bad accumulator. The accumulator is just a steel container with an elastic wall inside. One side of the elastic wall is charged (or should be charged) with nitrogen gas. The other side is the hydraulic fluid in your system. when the pump runs it pushes hydraulic fluid against the divider which compresses the nitrogen gas. This continues until the pressure limit of the system is reached, sensed by the pressure switch. The compressed gas stores the pressure and is supposed to release it back into the braking system when you step on the brakes in the form of assist.

If the Accumulator is bad, the nitrogen charge has escaped into the brake fluid and then out into the atmosphere. The accumulator is no longer able to store any pressure, and fills up with brake fluid. This leads to the pump having to run more often than it otherwise should.

This does not lead to the ABS pump running all the time, even with the key off. That is a different problem.
 
Ahhh gotcha.. and a couple people on here gave me some things to check, but this method of brakes is frustrating to say the least. I'm ready to throw in the towel and convert it to the crown Vic brakes or whatever. This is my daily, or supposed to be, and at 66xxx miles the entire brakes fail lol.. but anyway, what should I check for the continuous running issue do you think? What the other person said before in this post?
 
The pressure switch breaks ground to the pump motor when brake fluid pressure reaches a certain PSI (about 2300 psi)....

Bad pressure switches usually will either cause the pump motor to not run at all or run all the time only when the ignition key is on.....

If the pump motor runs when there is no key in the ignition, then the relay must be stuck in the closed position allowing power to go to the pump motor or you have something wrong in the wiring harness.....

These units are not that hard to diagnose and work on....
 
I'd put my money on a relay before the wire harness, everything else appears to beclean and closed on it but yes still a possibility I suppose. So, so far it could be a pressure switch and accumulator. ?
 
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