ABS mess

90 sc

Registered User
out of the blue I had a very hard pedal, and almost no brakes. Did some research and started with a new abs relay. Did not work, found the pump not running. Replaced the pressure switch, pump started running, brakes now started working, except when you panic brake. When you hit the pedal fast it is very diff. to press but if you let off a little you can feel a little click in the pedal and then it will operate normally. I purchaced a new accumulator and installed it today and it still does the same thing. My question is what should I replace now? The pump seems to run and cycle as normal and the brakes work great for normal driving, but if someone slams on the brakes, I need to pump the pedal to get it to stop fast. Thanks for any advice
 
Have someone work with you to test things. Have someone sit in the car and you have the hood open and put your hand on the abs accumulator. Have them pump the pedal with the key off until it gets very hard. Then with your hand on the accumulator have them key on, engine off. The pump should start running.

You should feel it vibrate at a very high frequency and the person inside should notice the pedal soften up right away.

If the frequency is low, and it takes a while for the pedal to get hard, the problem is a bad pump motor or poor quality connection. Check all the connectors.

I've gotten one motor rebuilt that was working, but I wanted to get it freshened up. They put new bearings and cleaned up the brushes. $100. I have one motor that was failing. It would work sometimes, but most of the time not. That one is gonna cost me around $200 to fix. They are rewinding the armature and need to make new brushes by hand. It's an old school electric motor company.
 
I will give it a shot, I can feel the pump motor kick on every time I hit the brakes , it vibrates on the pedal. Should it kick on everytime you hit the brakes or should the accumulator "store " some pressure? Thanks, also I got a new abs computer from ebay and I was going to throw it in tonite.
 
It shouldn't have to come on every time unless it is heating up and shutting down before it fully builds pressure. You should have a good 3 uses of the pedal before the pump needs to cycle.

Pumping the pedal also shouldn't build more pressure unless there is air in the lines, as the movement of the brake pedal doesn't create hydraulic pressure, only the hydraulic pump creates any pressure.

A good running pump will run like buzzzz. and be done.

A bad running pump will run like buzzz...buzzzzzz.... buzzzzzzzzzzzzzzzzz and then finally get done.
 
Well im leaning tword the pump. I forgot to mention that everytime i hit the pedal, the red brake light comes on for about 3 seconds then goes out. Do you have any reccomendations on where to get the pump rebuild or get a new one reasonable? thanks
 
the red brake light only. The abs light works on start up. Wondering if there isn't another problem?
 
Did you buy a new accumulator or a used one? :rolleyes: Needs to be brand new to work properly.
(just noticed ed's reply as well)
Well, I bought a used one. I guess I will try to find a new one and try it out. I was messin around with it tonite, and as soon as you press the pedal the pump kicks on ,every single time,as well as the brake light for 1.5 sec every single time. Brake fluid is good need to check the e-brake. Thanks for the help so far, gettin closer!
 
As a reminder for eveyone, be sure to pump the pedal 20 times with the key off before you remove it.. experience speaks here.

I had an old and tired one that I assumed wouldn't hold any charge.. it still had enough to spray a mess of fluid all over when I loosened it. :eek:
 
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Not to mention the fact that it gets brake fluid all over the DS cat.....:mad:

It takes a while to burn it all off.......:rolleyes:
 
When you install the new accumulator, do you need to put any fluid into it or do you just screw it on? I just screwed the new (used) one on and I lost around a half cup of fluid. I ordered a brand new accumulator so I hope this solves the problem
 
you can't add anything to a new one. There won't be room. Just screw it on. It uses up brake fluid when the hydraulic pump is able to offset the pressure built into the accumulator to effectively store pressure.
 
Does anyone know where to get a new accumulator without a 2month back order? Priorreman said end of Oct, spinning wheels said end of sept, the dealer can get me one for 325.00. Any suggestions??
 
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