I have searched the site and could not find an answer to my problem but did find some similar problems. 99 F-150 4.6 off road and tow pkg.
Last deer season after many hours off road but not necessarily 4 wheeling the truck started to lock the rear wheels and this engages the rear ABS. the pedal becomes very sensative to pressure and I have to be very carefull or I will squeake and squeal all over the road. I did a little troubleshooting on the dirt and found that it was super easy to get the rear tires to lockup and engage the abs. Now while I was hunting I would often overshoot the turn I was going to take and while tryong to stop would cause the brakes to lock up and then ABS would kick in and after the first time it was easier to lock the rear tires and do the ABS chatter dance. I finally took the wheels off and could see where the adjusting screw had spread out.(the threads were cleaner in some spots). I put some slop in the adjustment and the problem stopped for about 6 months.
Well I went off road for the first time in a while and had to slow down fast. The ABS kicked in and the truck is doing the ABS chatter dance again. It is worse the first time the truck is driven, not always in the morning, but will worsen after it has sat.the smoother the road is the easier it is to dance. I live in the Mojave desert and we have had no rain in months, the humidity is next to nill. I just had the Ford house do the 30K insp and the rear brakes are at 58%.
I have an appt next month to have it looked at, but in the mean time any suggestions?

thanks
JimP.

 

[updated:LAST EDITED ON 28-Jun-02 AT 04:43 PM (EST)]I had a similar experience with my 97. The right rear brake would lock up easily...very sensitive brake pedal, especially after the truck was parked for a while. I can't say that I was able to feel the ABS kicking in, but the problem was definitely worse when the ABS was disabled (pulled the fuse to troubleshoot).

I came to the conclusion that the shoes were contaminated...I believe it was the result of the Ziebart rustproofing. I replaced the brakes and flushed the brake lines and all has been fine since.

I hope this helps.

 

The Techs at ford said that my rear drums were out of round. They turned them and now everything works pretty much as new. $62.50 because of the extended warranty. Also had them replace the front pads and turn the disk for $182.00.I guess I can put it to the test as far as how well it was fixed the next time I activate the ABS in the dirt. It does seem to take more to get the ABS to come on in the pavement.
JimP

 

 

I have a similar problem with rear brake lock up. I have a '99 F150 4x4 5.4l automatic, extended cab w short bed.

Here is my story. In dry weather the brakes work fine. In wet weather they work fine so long as you use them often, ie as in driving around town and use the brakes at least every 20 minutes or so. BUT if you drive in the rain and don't use them frequently as in traveling on the interstate for > 1hour, then try to use brakes the rear will start grabbing! Also if you are town driving in the rain, and stop driving for the day , the next morning on first use the rears lock up! Even if it is a dry day. A few good stomps of the pedal and the brakes work fine.

Disabling the ABS has no effect on this problem.

Is there any other feedback in the system that is try to sense wheel speed or vehicle load that might be trying to disable or weaken the front brake pressure?

I suspect there is some sensor or cable that is getting moisture in it that is fouling things up.

Remember my problem only shows up during wet weather...humm....

I don't tow, don't carry heavy stuff and don't off-road with this truck.
I have the stock issue tires and wheels, FWIW. 16" rims.

Joe