ABS brakes Stopped working.

ironart13

Registered User
I got my 1990 sc smogged yesterday and when it was done and i went to leave i barely had any brakes. I swapped out the relay type fuse by the passenger side firewall but NO Luck! Then with a wire we jumped and bypassed the relay fuse and then the pump started working,but then you can't shut it off. We put it on the Comp and it threw codes 31 and 21.DOES ANYONE KNOW WHAT IS WRONG, OR HOW TO FIX THE PROB? I don't know if it's the Computer or what. Please help! Tony. Ca.
 
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Well I'm leaning towards the relay you swapped might have different internals because if you jumped it with a wire and it works and with the relay in it won't work, I'd say go buy the right relay.

Now about it not shutting off, thats due to the pressure switch. Replace it and the relay too for good measure, and you should get abs working. The computer has nothing to do with the pumps operation, only when to engage the abs to whichever wheels are sliding.

I got a switch for a buick electra 1987 from a buick dealer and it works. It was a lot cheaper than going to Ford for the same switch. The buicks also used a TEVES ABS system. I don't have a part number anymore, but I think if you search here for pressure switch, you can come across some info. I think it cost me around $85.00 and the switch mounts to the pump under the master cylinder resovoir and it takes a special socket to remove it. I think you can use an oil pres. sending unit socket to fit it.

More than likely you'll need to go to a dealer for the switch. I wasn't able to find one at any parts stores.

Also the relay is part number MR-76 according to Auto Zone and is $8.99 I recall it being MR-132 for some reason and having to special order it, but I can't seem to get it to come up with that number anymore so maybe it's been superceded or something.

If you are up to an afternoon job, you could just convert to vacuum boosted power brakes and do away with the abs. It's not too hard to do. And can be done for around $100.00 with parts from a parts store.

You need:

Brake Booster from a 1989 TBird base model
Master cylinder with resovoir from a 1993 Crown Victoria (not the police interceptor)
Then you remove the pump, and master cylinder, install the booster, install the new master, re-use your lines, and run a vacuum source for the booster.

Your lines may be a bit to long so you can either cut and flare them shorter, or just curl them around to make them fit.

Read this and learn all you ever wanted to know about the Ford Teves Mark II ABS System on 89-92 SC's.
http://www.albeedigital.com/supercoupe/articles/abs-system.html

The FORD Shop Manual states that if the Pressure Switch is replaced the Hydraulic Pump Motor Relay should be replaced as well.
 
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my abs

When i swapped the relay out with my friends SC i got no change. That's when we used the wire to jump it to see if the pump would even kick on, and it did! The relay we swapped with to check it, works in his car soo it's not that right?
 
abs brakes

And what i meant by it not shutting off was with the jumper wire making the pump work, which it does, it will just constantly keep running right? and would'nt that over pressurize the system? Or will something stop the power when it is pressurized enough? Thanks Tony.
 
Ok, I would bet money that the pressure switch failed.

Your relay is good, but change it regardless, the ford shop manual says to when you change the pressure switch.

The pump does run so you know its not burnt up. You can over pressurize the accumulator and damage it if the pump runs constantly, so I'd get the new switch ASAP and put it on along with a brand new relay.

Mine had a bad relay and I changed it, the brakes worked. Then later the switch failed and the pump wouldn't run. I grounded the one pin from the harness and the pump ran so I knew the pump was good. I changed the switch and then they have been fine for 3 years now.

Read that article I linked, it will explain how the system works. I truely believe your ABS Pressure Switch is bad. I don't know a part number off hand but you'll need to get it from Ford or from GM.

I got one from an 87 Buick Electra Park Avenue.
 
Which relay did you swap?

There are 2 relays for the ABS; one of them controls the warning indicators on the instrument panel when it gets signal from the ABS controller, the other (the ABS Pump relay - AKA Brown Pump Relay) controls power to the pump via the pressure sensor/switch. The "warning" relay is a standard accessory relay and the pump relay uses a GP Sorensen MR-120 (or equivalent). If the relay isn't the problem, and the pump works when jumpered, check the wiring connector at the pressure sensor. The problem is most likely a bad connector or a bad pressure sensor...
 
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