Anti- Lock brake problem

I hane an 88 turbo coupe and revently the anti-lock and brake lights have come on. The peadle is rock hard and car barely stops. A local garage run the codes and said its the master cylinder. The only place I can find one is Parts America and they want $1500. Dose anyone know if first anthing would give a false master code and second where to get a master at a resonable price.

Just for peace of mind, check out this article.
http://www.turbotbird.com/FAQpage/FAQpag..._Diagnosis
That relay is housed under the black plastic cover directly under the vacuum tree.

If the relay isn't the problem then check the pressure switch:
http://natomessageboard.com/cgi-bin/ulti...710#000003

Not sure if you an still buy a pressure switch.

If you need parts try contacting SIA Electronics, Inc. 800-327-6338 or 618-542-3919. They carry some parts. That's where the previous owner of my white car got as pump motor

You can also check the for sale section both here and on Turboford; antilock brake boosters with valve assemblys seem to come up for sale fairly regularly. That's how I fixed my valve body problem.

More often than not the relay is the problem... I did get a stuck pump motor started by tapping it with a hammer a few times...

As noted above, probably the relay. You are not the first member here who was told by a "mechanic" (and I use that word loosely) that the $1500 MC was bad when the problem was just a $20 relay.

A bad pump motor or relay will NOT set any ABS codes!! THat part of the system is 100% independant of the ABS, and has no connection with the ABS computer..... You can remove the pump and relay, throw them in the garbage, and the ABS computer wouldnt know it.

If you do end up needing a new MC setup, I have one for sale in the For Sale forum for $30 plus shipping. It was working great when removed about a year and a half ago....Tommy

Originally posted by Jeff K:


A bad pump motor or relay will NOT set any ABS codes!! THat part of the system is 100% independant of the ABS, and has no connection with the ABS computer..... You can remove the pump and relay, throw them in the garbage, and the ABS computer wouldnt know it.

Jeff, I had a different experience.

My ABS light came on when I blew a caliper getting on the freeway and dumped all the fluid out. Both it and the brake light were on. And this past summer I was an idiot and ran it dry bleeding them. Again both lights came on when the pedal got hard; and the pump was not operating any more.
I did check for codes because it did not cross my mind I hadn't filled up the reservoir, and there were no codes thrown. I tripped over the bottle of brake fluid dumping it everywhere on the ground and that reminded me I hadn't filled it after the other side flush. :mad:
And that was my last big bottle.

Would the ABS monitor proper brake pressure to activate otherwise the light stays on?

You are mostly correct, Matt. If the system looses pressure due to a bad relay, pump, blown hose, etc, the pressure switch on the MC that also turns the pump on and off will turn on the ABS and BRAKE lights. One or both lights will also turn on if fluid level gets low.... if just a little low, ABS light goes on, if critically low, BRAKE light will also turn on. However, none of these situations (pressure loss, low fluid level) will set any codes in the ABS computer.

Originally posted by Jeff K:
One or both lights will also turn on if fluid level gets low.... if just a little low, ABS light goes on, if critically low, BRAKE light will also turn on.

You sure about that Jeff??? I've seen the red brake light on with low fluid in several different TCs. Never seen the amber ABS light with just low fluid... Of course it will come on if there is severly low fluid, as there won't be enough to fill the acclumator and build pressure.

Tom, not 100% sure, but I think I am at least close to correct. Been a while since I studied the ABS wiring diagram, but from what I remember, the low fluid switch assy has 2 or maybe 3 seperate magnetic reed switches in it. One of the switches for sure closes a circuit that turns on the BRAKE light, but I forget the exact function of the other one (or 2?) switch(es). The other switch(es) either turns on the ABS light, or disables the ABS system, which then turns on the ABS light, or both. That part of the circuit isnt shown in the EVTM, only in the complete ABS wiring diagram in the ABS troubleshooting part of the Helm (Ford) manuals.

One thing I do remember is that the wiring for the 2 (or 3) low level switches, and the wiring for the 3 seperate switches housed in the pressure switch is kind of weird. Took me a long time staring at the diagram to figure out exacly how it worked. That manual is in the garage, and I dont feel like going out to get it.... it is 10 deg and windy here right now