Well; i have kind of been putting this off... It all started when my other rear end went out. My brake lights on the dash came(and stayed) on. The brakes still worked pretty decent, but in reverse if you had to pump the pedal or just let off and hit it right away again for any reason it would just build a bunch of pressure on the pedal, and didnt hardly want to stop. Well. The ABS ring in the old rear end(what the little sensor on top of the rear end gets its reading from) was chewed all to pieces by the pieces of pinion teeth hitting it/chewing it up. So i pretty much figured that was the cause of my problems. Well. I got the new rear end in, and it still does the same exact thing. The passenger side(i believe) bleeder broke off when i was trying to get it out. We did get the other side bleeder loose where fluid would come out, but we never got any air out of the line. My parking brake is also not near as good as it was. The brake pads on this rear end arent hardly as thick as the ones on my old one, but i dont know if that is the problem. So anyway. The problem is that my brake light's are always on, the parking brake doesent work near as well, and i cant hardly stop in reverse. It stops pretty well going forward, but if you are moving real slow, and backing up/pulling up a bunch it doesent want to stop to great going forward either. Thanks for any help anyone has, and sorry for the book .

Eric

 

Sounds like your brakes are way out of adjustment but doesn't explain the light.
I would start by adjusting the rears. I just explained how to here>
https://www.dieseltruckresource.com/...t=87297&page=2

Don't know if you had the shoes off but if the front and rear shoes are reversed the brakes dont work well backing up.