ok... So heres the deal... On the 05 GMC sierra, the truck was hooked up with a tow package... all I had to do was add the 7 way plug (so im guessing that means the tow package is there ha) anyway brake lights, signals etc work great... Now I bought a 20' used trailer tandem, that looks like it has a brake on each 4 wheels. I bought a brake controler and the wiring harness. Hooked the harness into the box by the brake pedal, wired in the brake controller, and when I push the brake the little decimal point shows up on the controler like Draw-tite says it should. Now the trailer has very bad looking wiring.. rusts etc etc. On the brake controler, there are no numbers (for which brake setting it is on.) Do these ONLY come up when it detects a trailer? or should they be there no matter what? When I hook the trailer up.. nothing happens.. brake lights good, turn signals good (Although they are backwards.) but no brakes. My plan is to rewire the trailer completely.. So I went out and bought a wire kit. New 7 pin plug aswell.... My question is, for the 4 brakes, how do I connect them with one wire? Also, does the battery and brakeaway need to be hooked up for this to work or is it only a backup? Thanks.. I think I found a wiring diagram for the trailer.. same company.. it just says diagram for utility trailers, so im guessing its like the one i have.. i know it is a 1994 model as well.. Thank you VERY much for your help... I have been very stressed about this!