Trailer Wiring/Access pwr

03GMCSierra4.8L · November 3, 2003

Ok, I must be missing something! I have hooked up a 7 pin Trailer plug to my 8 wire harness on my 03 Sierra. Everything works with the exception of the Acc terminal which is to charge the trailer battery and the Brake Terminal (I dont have a controller installed yet). Under the hood in the Elect Center I have a fuse in Stud 2 and I put a fuse in to test the system in Stud 1. No power to the Acc term on the Trailer connector. Do I need a Brake Controller plugged in also for this Acc terminal to function? If someone knows what I have overlooked, let me know!

Also, I am a bit old school taught on brake contollers....I have grew up around the mech hyd operated ones that tapped in the Master cylinder! (ages me, dosnt it!).

What are you opinions on the time delay models vrs the inertia models? I will be pulling no more then a 22-24' travel trailer. I am leaning to the time delay from the basis of "simpler the better" but I need some imput from those who have experience with these.

Thanks for your feedback!

Shaners · November 3, 2003

The '03 trucks are a little different than the '99-'02 models. Someone with an '03 will be able to help you out because I know this subject has been discussed before.

I would highly recommend a Takonsha brake controller for your truck. They are the best on the market as far as I'm concerned.

03GMCSierra4.8L · November 4, 2003

Mystery Solved.......I had to add the 30 amp fuse to the "Stud 1" location. Ok so did that and figured I was all set. NOT! Thank you GM.....I also found the 12V Red Lead with a ring tounge attached to it in the underhood elect center. That had to be hooked up under the elect center side cover on the stud closest to the "Stud 1" fuse that I just installed. Did that....oh, and you will need to supply the M6 x 1 nut that you will need.....Everything works. I do notice that its a constant on 12v to the trailer connector....so I would think you would want to be careful on leaving the trailer plugged in or else it will run down the truck battery.

You would think that if GM has installed the 8 wire trailer harness that they would hook up the wire in the elect center. I got it, that would mean them adding (1) M6 nut to the vehicle! Cost Reduction!