Porofinoblue

On my '93 F150 V8 5.8 I just recently replaced the pad, shoes, rear wheel cylinders, calipers & put on a used master cylinder. After that the ABS & brake light would come on after driving a while & if you kept going with the truck the back passenger locks up, it doesn't appear to happen to the driver side. I drive 11 miles to work & if I always slowly stop the lights don't come on till I'm pulling I'll into work. I looked around & couldn't see anything wrong with the things I replaced so I took it to a mechanic and of course he didn't have that problem driving it and the only thing he could find was the ABS control module was going bad so i replaced that but still didn't fix it. I thought maybe it was a faulty wheel cylinder so i tried replacing that again but the lights still came on with the new one so I'm out of ideas at the moment. Anyone have suggestions?

kd3pc

master cylinder....the reservoir has a sensor that when not satisfied, will light both lights.
it also has check valves and internal seals that when bad, give the symptoms you have.

Lines, Master cylinder, ABS, proportion/control valve and if your year has it, the antidive lever control under the bed and above the rear.

Steve83

Why? Those are not maintenance items - they should only be replaced if they fail a published test. What exactly made you replace them?Why not reman or new? They're not expensive or hard-to-find.That indicates low fluid in the MC reservoir, or a sunken float.That's an entirely separate problem. Click this & read the caption:


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Then read this one & the NEXT two dozen in this album:


(phone app link)Did he tell you what exactly made him think it was GOING bad? IME, parts are either good or bad - you can't tell when they're about to go. Read this & the NEXT few:


(phone app link)STOP replacing parts. Take the time to learn what the lights mean (read the owner's manual, the Haynes manual, & those captions) and how the system works (and it has a LOT of parts, so read ALL the disk & drum captions in that album), and the proper ways to maintain & repair it (in Haynes).


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