abs motor question

dirtyredghost

Registered User
so just bought a rust free 90 sc that runs and drives great for 900 bucks!!! odometer shows 106,000 on it, and even the air works. all stock besides air filter, problem is like alot of them, the abs and brake lights are on. i read on here threw a few posts and knew to check for power ect. i used a jump wire to bypass the relay and after tapping on the abs motor it now hums with wire plugged in.(new abs relay will be in tomorrow at parts store). its been a while since i had an SC but i seem to remember the pumps being audible from inside the car. mine you can barely hear with engine not running standing on drivers side with hood open. lights are still on no matter how long i leave motor running (ran 2 min roughly) and pedal is still rock hard. since i wasnt relying on the relay to operate the motor/turn it on or off, it being hard wired i would have thought shoulda made it work at least to a point. my questions are.......1)how loud should the motor be? 2)if motor is the issue, how do i go about getting it rebuilt? and 3) if what i described seems to be motors normal operation, where do i go next? any help would def be much appriciated. im not rich by any means, but i would like to keep this car in original working condition considering how clean and original it is.
 
I just R&R'ed a friend's ABS motor and pump and it is like that. I had to put my hand on it to be sure it is running. After the pump primed and started pumping fluid it got a little louder but still, is very quiet. I have mine rebuilt by the ABS Tech, Jose Nunez, in Dallas, 214-579-7846. He charges $140 including return shipping.
 
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Update.....put the new relay in this morning and drove threw town and hit the brakes and feeling alot better. Abs light even went off until i press the pedal. But i only drove it about 2 miles. Problem is i topped the brake fluid off last night without reading the side of it. So needless to say as it built pressure up today it pushed brake fluid out all over the ground lol. Hopefully the brakes will work correctly once it all balances
 
The motor may be working fine. Mine is pretty quiet. With the car off, you have to listen a little it. Hard to hear when the car is running. You have to feel it through the brake pedal to be sure it's running.

If it's not building pressure, then either the pump is airlocked, or something in the pump is worn out. (Or you are out of brake fluid! ... but I assumed you had checked that.) You can test the pump's operation (approximately) by removing the accumulator ball and activating the pump motor. If a little geyser of brake fluid shoots up a couple of inches, then it seems to be fine. If not, maybe you need a used or rebuilt pump.

Also, tapping on the motor is not necessarily a great sign. The brushes may be on their way out. Then again, maybe there was just some damp brush dust shorting the commutator and you knocked it loose and things will be fine. Hard to say. But I would expect that new motor brushes might be in order sometime in the future.

Board member the-big-e can usually provide good used or rebuilt ABS parts.
 
Update.....put the new relay in this morning and drove threw town and hit the brakes and feeling alot better. Abs light even went off until i press the pedal. But i only drove it about 2 miles. Problem is i topped the brake fluid off last night without reading the side of it. So needless to say as it built pressure up today it pushed brake fluid out all over the ground lol. Hopefully the brakes will work correctly once it all balances

If the light continues to come on when applying the brake only and the pump is functiona, and the fluid level is full,l then that is usually indicative that the accumulator needs replaced. That is the big black ball that sits atop the mast cyliner. It has a rubber bladder inside that has compressed nitrogen on one side of the bladder. Over time the nitrogen leaks out.
 
When the ABS and brake lights come on when you hit the brakes, your SC is telling you that the accumulator needs to be replaced.....
 
My lights went through a phase where they came on when I would hit the pedal ... now they are steady on and the pedal is hard all the time... I checked to see if my motor was running as well and very faintly I can hear it ... does that mean my accumulator is the problem too?
 
It could be......

Did they ever flicker on when you hit the brake pedal...

Try what was mentioned above and take the accumulator off...

A good pump / motor combo will shoot about a 1½" geyser of brake fluid out of the accumulator fitting....
 
Well it tried to work the one time yesterday and that is it. Since then pedals been rock hard and lights are on. So ill be pulling the accumulator ball off to check but most likely it is gonna get a rebuilt abs motor and new accumulator both. I really didnt want to spend toooo much money trying to fix it but with the condition of the car and the fact its all original i really dont want to trash the abs set up and put a conventional brake setup on even if it is cheaper
 
So, the accumulator says that is contains brake fluid under high pressure and not to remove it? how do you remove it, loosen it slightly and let the pressure release? then will it fill itself back up?
 
i read in another post that you should pump the brakes with car off like 50 times to make sure you relieve the pressure and then its safe to take it off
 
abs pump

If you just let the car sit over night the unit will depressurize it self. The last time I pumped the pressure down via the peddle it caused a valve in the pump jam and I had to have rebuilt.
 
I normally pump the pedal with the ignition switched off 100 times. On one occasion I didn't pump the pressure down enough and had quite a spray of fluid come out. With full pressure it can be dangerous to remove it.
 
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