ABS light on Dealer says computer bad. | Ford Explorer Forums - Serious Explorations

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ABS light on Dealer says computer bad.


Well-Known Member
November 3, 1999
Reaction score
City, State
Fullerton Ca.
Year, Model & Trim Level
94 4X4 XLT 4 Door
O.K. Here's is the problem. ABS light on, took it to the dealer they did a diagnostic and said the "hydraulic control unit" was bad. I asked what it was and the cost to replace. They told me it is the ABS computer and the cost to replace it is $1300. I went to my local salvage yard and got a used unit and installed it but the ABS light is still on, returned it thinking it was bad and got another....same thing. Can I do a diagnostic with my code scanner? I saw a port marked ABS that is the same as the engine test port, and my scanner fits it. I need to get this fixed soon. Can anybody help?

1994 Explorer 4X4 XLT


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If you find this to be true that it is the ABS computer, I have one for sale that worked perfect before removal. I would check the sensors first though. One ate each tire in the front behind the brake disks and one in the rear on the top of the diff.

I thought about that...but can I get codes from the computer if it is working? And if so what are the codes for the sensors? I don't want to replace them and find otu they are still ok.

are you having braking problems or is the light just on? the abs light has been lit up in my '92 for about 3 years now, and when the dealer checked it they told me it was the rear abs valve (rabs valve) and that I'd be better off without it.

So, moral of my story is to not worry about it if you're not having any braking troubles.


Well no real problems.....but my X stops poorly as it is. I had to do an emergency stop on the freeway and wound up sideways due to the front left brake locking up. I never had that problem while the abs was working. Plus I like to keep my truck in the best mechanical condition possible.

Did the dealer say it was the computer or the hydrolic control unit. You mentioned both in your original post. I do have both of those parts sitting in my garage if you need them. I don't know of any codes or how to test it but if you went to the dealer and they told you it was one or the other I am sure they are right as they used a computer to diagnose it.

The dealer told me the hydraulic control unit had failed. I had no idea what it was, so I asked, and the service advisor asked the tech and he said it was the "computer" so I assumed the he ment the ABS computer on the fender well.
What is the "Hydraulic control unit" if it's not the computer?

Thanks for the help!

Well, I thought the HCU was the unit that the actual brake lines hook up to. If you follow the wires from the computer and the hard brake lines from the master cylinder, the HCU sit just forward and above the steering box on the driverside frame rail. Just left and to the rear of the rdiator. I know the computer controlls it but I am not sure of it's actuall nomenclature. I can check the Chilton's manual at home tomorrow and get back to you but I am pretty sure.

Thanks! I am soo confused.....and I'm not a car dummy!
I am stuck with the computer I bought...they won't let me return it. So if anybody needs one, I'll sell it!

Check your wiring. I have a loose wire that goes into the ABS controller dealy on the frame (RABS) and sometimes it jiggles loose. It makes the light come one and the ABS stop working. I haven't bothered to fix it yet but you may be having a similar problem.

Thanks Paul,

I'll look at the wireing! As for Diff, did you have a chance to look at the manual?

Thanks for the help everybody!

ABS Diagnostics

Your engine computer code reader may work with your antilock brake test connector. Mine does - To try it, turn off the ignition, put the tester in the HOLD position, then go turn the ignition on (but don't start the car). Now go back to the tester and flip the hold switch to the test position. It will pulse the light and give you the error codes, if any. Code 16 (one blink - one pause 6 blinks) means it can't detect any problem. Code 17 means the power was disconnected to the abs unit (you may have pulled the fuse). Any other code - post the light blinking sequence and I'll tell you what the book says. You may get more than one code. each two digit code is followed by a longer pause - watch the light until it stops flashing for 30 seconds.
To unplug the tester, turn off the ignition and unplug the tester.

Sounds like the RABS switch to me.

3 year old thread..