Hello,

So I have a 1999 f150 v6 Xl RWD. My abs has been on for a long time and its been a year project. I know sad right? Here are the symptoms.
-rear wheels lock up before front.
--wheel and brake shake at any speed
Ok so here is what ive done.

-Replaced master cylinder
-replaced all brake lines back from master cylinder to rear drums
-swapped abs sensor in back 3 times
- replaced rear wheel cyilnders
-swapped (proportioning valve?) below master cylinder with another one but it was used from a junkyard of a recent crash (same truck exactly)

So i brought the truck to my buddies garage and he hooked up his snap on reader and it came up with some gibberish saying look behind glovebox area so we couldnt read the code. Any help please!!!!

 

If rear wheel locks up before front wheel, it doesn't sound like an abs problem. If it is an abs problem, disabling abs should remove the symptoms. You can test it out.

I wonder if the problem is with the front brakes. You already replaced master cylinder and proportioning valve. What about metering valve? Can it fail to deliver pressure to the front even after rear reaches sufficient pressure? I am just guessing.

By the way, on which wheel do you have abs?

 

just rear abs. My orange ABS light has been on and thats why im thinking its abs. We have gone over the brakes multiple times to make sure the mechanics are right. Hmm metering valve is that behind the proportioning valve?

 

If your wheels are locking up, the ABS system is probably not working at all. Could be electrical. Checked the ABS system fuse?

 

ill check today. Is there any trick to getting the abs light to flash so you can narrow the problem down?

 

I don't know of any way.
Generally when you fix the problem the ABS light just goes away.
It could also be the module itself is bad.
I think the module is located behind the dash so that might fit in with your earlier error code posting.
WARNING - If the ABS light is on or the ABS does not work because of the fuse you may have the Ford cruise control brake sensor recall problem. That sensor is on the same circuit as the ABS. THAT SENSOR WAS RECALLED DUE TO A FIRE RISK. Go to Ford's site, enter your VIN and find out if the recall has been done. If not, your truck could catch on fire at any second even while sitting in the driveway.

 

What I am suggesting is it's easy to eliminate abs from the equation by pulling the abs fuse. If the rear wheel still locks up, you will know it has nothing to do with malfunctioning abs. And you can solve lockup and abs separately.

I don't know exactly where metering valve is, but often it is co-located with proportioning valve. I am not a mechanic and am just bringing up possibilities.

 

I tried pulling the fuse, number 15 i believe in the dash. When i tried to start my pickup it wouldnt let me shift out of park.