Need help with abs

sfanucchi

Registered User
I just bought my 8th thunderbird yesterday. Got it for 200 cause of a brake problem. So here's the deal. Antilock light is always on. And the brake pedal is hard. I tried scanning the abs computer but it won't let me. It won't connect to it . So I think the computer is fried. Now also the abs motor doesn't turn on at all. The weird thing is if I remove the abs relay under the hood and use a jumper the pump goes on But it doesnt ever shut off. It just keeps pumping I've tried a few new relays and they don't turn the pump on. It only works if I jump it. Any ideas on how I can make my brakes work properly again
 
http://www.sccoa.com/forums/showthread.php?t=117984&highlight=abs

This was in a "Members only" post. Might help. Figured if you couldn't get to the post I would copy and paste it out.

Originally Posted by the-big-e View Post
I've seen this on a number of SCs....

This may sound dumb, but are you sure you checked the brown ABS relay for proper operation....

I personally tested the pump motor that I sent you, so I know that is not the problem....

If there is no power going to the motor, then back track to the relay....

If no power there, then things get a bit more involved....

Describe exactly what happened when the brakes went out.....

Did they just fade away over time, or did you get in the car one day and they were gone.....

It could be your pressure switch is bad (stuck open)....
 
I know a relay is a relay, but are you sure you have the correct ABS relay....

You can use a 9v battery to check proper relay operation....

Apply voltage to the two small terminals on the relay and you should hear and feel the relay click....

If the relay is alright, then I would lean toward a bad ABS pressure switch....

When the pressure switch is in it's normal position, it completes the circuit to the pump motor....

The relay activates and the pump motor will turn on...

Once a prescribed pressure is reached, the pressure switch breaks ground to the relay causing the motor to shut off....

When you use the jumper wire, does the pump motor start to bog down after a minute or two....:confused:

One other thing that could also be causing your problem is a bad ignition switch....
 
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If new relays don't solve the problem and you are sure you have the correct relay, you could have a bad pressure switch or a wiring problem. As described above, the pressure switch is in-line with the relay and the motor, thus it's failure could cause the pump to not turn on when you have a good relay.

Some advanced trouble shooting is documented here:
http://www.35thatr.org/Tips/ABS.htm
 
so ive figured out the relay is ok and the pressure switch is no good i grounded pin 4 on the pressure switch connnector and the relay clicked and pump turned on !!!!

so now where do i find a pressure switch ?? can you even get them anymore?
 
so ive figured out the relay is ok and the pressure switch is no good i grounded pin 4 on the pressure switch connnector and the relay clicked and pump turned on !!!!

so now where do i find a pressure switch ?? can you even get them anymore?

I've got one, 15$ shipped to your door. Click on the "PIC" link for a picture.

Pressure switch for Teves II -- 1 available PIC
 
If it has a warranty I suppose. Many new accumulators are really just never installed older stock. Due to the design, the accumulator has a limited shelf life, such that a new one sitting on the shelf for 10 years is nearly as useless as one in a car for the past 10 years. That may or may not be the case for the one you are looking at, just thought you should be aware.
 
Antilock light is always on. And the brake pedal is hard. I tried scanning the abs computer but it won't let me. It won't connect to it . So I think the computer is fried.

I wouldn't throw away your ABS computer. I have two working T-Birds and I cannot connect to either one with my code reader. I have read something about how I need to add a diode somewhere but I have not tried it.
 
So the new master cyl is in. And now I have power brakes. But my abs light is still on all the time, I don't get that
 
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