For about the last week or so, when I step on the brake pedal I hear a ratcheting sound. It's real quick 5 to 10 chi chi chi sound. It then goes away most of the time. Sometimes it keeps going at a real slow pace when fully stopped, but I can let off the brake pedal then step on it again and it will stop.
The sound seems to be coming from outside, but I can't determine where.
So what is it and do I need to fix it?
Oh it's on my 92 F150

 

When you're stopped the only part of the brake system that might make noise is the power booster. Try listening around there while someone else steps on the brakes for you.

Actually, wait a minute... does that truck have RABS? Rear anti-skid?

 

Yes it does have rabs. The light has been on and off forever ( actually been on and off about a year or just over). As long as I've had the truck. (since 2004) I doubted they ever worked.

The lines have been removed from the module or whatever it is on the driver side frame rail and connected together. This was done several months ago.