Here goes. Got this problem when braking. At beltway speeds when hard braking, back of truck jumps very bad. Faster the speed the worst jumping is to slow down. Even at lower speeds with light braking, it does it but not as bad. Replaced rotors and pads in the rear. Thought that was it. Still have the problem. The ebrake shoes look ok. A friend is telling me to check universal joints. One of them or both may be frozen up. It only does this when braking. I was wondering if anyone else had this problem.
2003 F150 4x4 5.4l. aBS brakes Thanks for reading. 11/1/10 today. I changed sensor for anti-lock brakes on rear end but did not help anything. 11/13/10 Replaced front rotors and pads. Replaced both universal joints. Had it checked with scanner. No codes. Still same problem.

 

sounds like it could be a bad proportioning valve... maybe you are dumping full pressure to the rear wheels and locking them up.

 

Is your parking brake fully released? I had the same problem, and a quick pull of the parking brake release cured the problem.

 

Thanks for info. Brake is released all the way.

 

I am having the same issues as you and have tried new rotors and pads on the rear as well. Still have a hopping bouncy truck. Gonna try replacing the front rotors next and see what happens. Maybe new shocks too. If you ever find a resolution please let us know.

 

it would seem more likely there's a problem with the fronts if the rear is hopping. as said maybe bad proportioning valve or stuck calipers. front pads worn way down and not grabbing.

 

Hi; This may sound a little crazy but my truck is OK now. After changing all kinds of parts that did not help anything. We unplugged the wire on the side of abs unit. Its the small one. I think it is for solenoids or power . Took for test drive. Abs light is on inside of cab. Did not have any problem with it disabled. Now we plugged wire back into ABS unit and went for test and my brakes are still OK. Does not feel any grabbing of rotors like I did before. Works perfert now. Ofcourse I have all new parts on truck. My truck was doing the jumping for over 10 months. I don't know if this will help you or not but if you have not disabled it yet/ you can try it. I was also told to replace brake fluid.
I am a happy camper now. Bill

 

Yeah I know this is an old thread but I figured I had better update since I solved my problem finally and may help someone in the future. I got new rotors and pads for the front and did kinda like Webturtle said and I pulled the fuse on the ABS for a short bit then plugged it back in and voila!!! No more bouncy truck!!! I cant really say it was one or the other but I know the new brakes definitely played a part. My next step was gonna be replace the proportioning valve but it doesnt look like I will need to do that. Thanks for the help again F150online!!

 

ok guys i just bought a 1997 ford f150 ext.cab 4by4 lariat the abs is kicking on for no reason i have replaced the front brakes and rotors and i noticed my back drivers side wheel cyilinder was linking so i replaced that figured the abs problem would go away but it didnt i half to leave the abs fuse out so the abs dont kick on and when i drive the truck for the first time of the day it seems like one of the rear wheels locks up and when im driving and go to apply the brakes it wheel start hopping i feel like im going to hit another car if i dont get this fixed i took it to a mechanic to check the abs problem out he said its cause it has the wrong size tires and rims the size is 285/75/r16 i dont think this would cause it it has a 4 inch lift please guys help me out