I bought a 99 F150 2x4 a few months ago. The ABS light has been on since I got it. I've had a couple of times over 3000 miles where the brake pedal vibrated when coming to a full stop. I don't know if this is normal ABS operation or not. Once I was in gravel so the rear wheels may have been slipping. The other day it did it again when on dry asphalt. It's a little spooky because both times I had much less braking effectiveness and overshot my stopping point. I could hear a sound like a motor running and could feel the vibration in the pedal, so I'm fairly sure it's the ABS. Looking for advice on what to do next. The brakes work great other than these two isolated incidents.

 

ABS sensors probably the issue. Pull them out and clean them and around where they seat on the spindel. Be carefull when pulling them out and putting them back. I broke one and it cost me $$$$$ Good luck

 

^ditto, although i just replaced mine so i didnt need to worry about cleaning them all the time. I had the same issue and i almost rear ended several cars.

 

Mines doing the same thing. Where do these sensors sit? I think somebody may have deleted them on my truck with the longer arms and lift spindles.

 

They sit right next to the top ball joint. You cant miss them. They could have on your truck you just wont have abs then.

 

Well that's great hahaha!

 

What's your brake fluid look like? Might want to replace all the fluid. Mine was doing the same but I changed the almost black brake fluid and it decreased dramatically, and then I cleaned the sensors and the vibrating was gone.

 

Ya it doesn't look so hot. Haha, I'm changed the brake booster tomorrow, the diaphragm inside it must have torn because it sounds like a turbo when I'm not on the brake pedal!