I know there are alot of topics on this but I am still not sure which one it is for me. First off I have a 99 F150 Flarside 5.4, rear drum, front disc and 4W ABS.
What is going on, when I am using soft braking at low speeds, almost to a stop, the pedal goes hard and pulsates. You can also hear the pulsaing from what sounds like the front end. The pulsating is consistant, not random. When that happens the brakes stop working and I will roll ahead for a little bit. If I just hold my foot on the brake at the same pressure it will stop after a few seconds and the truck will brake like normal. If I pump the brake a couple of times it will stop also. This happens pretty much every time i am coming to a soft stop, stop sign, traffic lights and all the bumper to bumper. I did pull off code c1230, which is the rear diff ABS sensor. I replaced the sensor and it is still doing it, but I almost does seem to be a little better. I do know that I need to replace the front pads and probally rotors,(back everything is new) which would lead me and alot of people to think that is the problem, but when my ABS light does come on the problem stops. The ABS light takes awhile to come on and it doesn't come on when I am braking but when I am giving the truck alot of gas, hard accelaration. Not sure if it makes a difference if I am turning in a specific direction or not though. That leads me to think it is and ABS problem. I was going to replace the two front ABS sensors but I wanted to get some advice from you guys first. If anyone has any ideas they would be greatly appreciated. Thank you everyone.
P.S please ingore the horrid spelling.

 

4WD or 2wd? Sounds like the rotors are warped. Bleed the brake fluid, rule that out but I'm thinking rotors. Especially if it's been a while for front brakes, maybe replacing will fix it, sounds that way anyways.

 

4wd.

 

Do you have any shuddering coming from the steering wheel? Usually a shudder on breaking would indicate warped rotors like Blue20004x4 was saying, but all the other symptoms point to ABS.

 

Sorry it took so long to reply. Took the truck into my friends shop last week and took the front wheels off and checked the rotors and they were not warped. While I had the wheels off I was inspecting a couple other things in the front end and in doing so I happened to notice the seal for the wheel bearing was just hanging there. So I will be replacing both wheel bearing assembles in the front end. Thinking that is the problem. Ordered the parts in just waiting for them to get here. Once I get them installed I will post back and let everyone know if that was the issue or not. Thank you for the replys though.

 

Got the assembles in and installed them both. I no longer have the pulsating on the brake pedal. Both bearings where gone on the front end..... Happy now that i can stop properly and i don't have to worry about a wheel coming off on me. Cant say for sure if it was the bearing or the wheel sensors causing the problem with the pedal but since they are all one peice.