Hello,
I have a 97 F150, 116k miles and 5.4.... just yesterday a clicking sound could be heard when the Brake pedal is pressed ( or just lightly depressed). Occurs at all speeds, is heard from inside the cab and sounds like its coming from just below or around the Master Cylinder or Brake Boost area. Faster you go, faster the clicking sound. No ABS light and Brakes do work normally at higher speed. At low speed <5mph feels like the ABS may be trying to kick in. And occasionally when maintaining continuous pressure until the truck is stopped the clicking will continue even after the vehicle is no longer in motion at about 1 click per 2 seconds.

Any Help would be appreciated.
Thanks.

 

Im having the same problem right now. I posted in the 2001-2003 Ford F150 forum to try and get some help but hopefully you can find something out here.

I just did a brake job on my 2001 Ford Screw 4x4 and it's making that clicking noise you are talking about. I cant figure it out.

Also when I press on the brake pedal it is really squeaky and it annoys me. i cant figure out how to lube the push rod for the brake master cylinder.