07 New Body Style Trailer Harness

seanndiane · September 24, 2007

1. The new body style (07)doesn't come with an under dash harness for brake controller. It has the wires there for integrated controller. I understand what the red/black, white, dark blue, and lightblue wires are for but what is the orange?

2. The truck has a 7 way factory plug on bumper but the red/black (hot/charge) wire doesn't work. I found the wire with a tag and connector under the hood, hooked it to the batt through a fuse and the brake controller started working but the bumper plug red/black wire is still dead. Any ideas?

zacman · September 24, 2007

Hi, I don't mean to hijack your thread but I have the same problem with a 2005 2500hd.(no power at the trailer plug in for the trailer power terminal.)thanks for any help.

lord-dogbert · September 24, 2007

On my 03 the trailer power fuse is under the hood fuse box, upper left corner when viewing from the side of the truck. It looks like there is something there but it's a dummy. Look in the glove box or the dealer has them for a few bucks.

That took care of my issues; well, at least that one.

seanndiane · September 24, 2007

The red /black wire runs next to the fuse box under the hood and is taped outside of the harness with a tag that says it is for aux trailer pwr. According to the owners manual it should be hooked up in the fuse box (i think it said number 70--stud). I wanted to use a circuit breaker insted of the fuse so i went straight to the battery. The manual says the tow/haul button shold be pushed in for increased voltage for charge rate. Maybe it HAS to go throught the fuse box (relay to the tow button or something)

Will try swapping it this afternoon and let you know.

As for the last post, I went straight to the battery so the fuse shouldn't have affected it.

asilverblazer · September 24, 2007

1) Panel illumination. It's not needed for most aftermarket controllers.

2) There is another wire that needs connected. \/ \/ \/

Both of those wires for auxillary power and trailer brakes are taped up under the hod, one below the brake booster and one behind the underhood electrical center. If those are not connected to the underhood electrical center studs they won't work. As for bypassing the underhood electrical center like is being described, I dunno, I don't see any gains from it considering the trucks electrical system was designed to be used as stated above, why go around it?

seanndiane · September 24, 2007

1) Panel illumination. It's not needed for most aftermarket controllers.

2) There is another wire that needs connected. \/ \/ \/

Both of those wires for auxillary power and trailer brakes are taped up under the hod, one below the brake booster and one behind the underhood electrical center. If those are not connected to the underhood electrical center studs they won't work. As for bypassing the underhood electrical center like is being described, I dunno, I don't see any gains from it considering the trucks electrical system was designed to be used as stated above, why go around it?

The reason for going around it is: I worked at an rv place for a few years and when we wired brake controllers we were required to use a resetable breaker instead of a fuse. Reason: If you start down a huge hill and the brake controller blows a fuse, you are out of luck till the bottom of the hill. If you use a breaker, after it opens it will reset allowing you another chance at brakes, maybe not for 30 or 40 seconds but aleast you have another shot at stopping your trailer.

I do appreciate your reply and will look for the other wire when I get home.

Thanks

asilverblazer · September 25, 2007

I see.

seanndiane · September 25, 2007

1) Panel illumination. It's not needed for most aftermarket controllers.

2) There is another wire that needs connected. \/ \/ \/

Both of those wires for auxillary power and trailer brakes are taped up under the hod, one below the brake booster and one behind the underhood electrical center. If those are not connected to the underhood electrical center studs they won't work. As for bypassing the underhood electrical center like is being described, I dunno, I don't see any gains from it considering the trucks electrical system was designed to be used as stated above, why go around it?

Thanks, you were dead on. Found the "other" unlabled wire on the harness below the brake master cyl, hooked it up and worked perfectly.

ZACMAN when you pull the cover off of the fuse block you will see the two studs at the front of the fuse block. They are different sizes for the two wires. You will need 2 metric nuts (different sizes) , the fuses are already in the block.

zacman · September 26, 2007

Hi I tried switching the fuses from stud #2 to stud #1 (#1 had a fake fuse in it) and that put power back to the plug in. Is it likely that the wires were put on the wrong posts at the factory?

daryl · October 4, 2007

Find everything you want at:

http://www.stealthv.com/images/GMT900_Trai...ler_Install.pdf

The guy who did this shows how everything works. Lots of photos on where the wires are, what to hook up, etc.

-- Daryl

lord-dogbert · October 15, 2007

I haven't checked mine yet but with the integrated brake controller is the brake wire already hooked up?

forrestf · October 16, 2007

My 06 Duramax had no 12 volt power to 7 pin trailer plug, installed 40 amp fuse in place of the red B+ dummy fuse @ stud #1 in fuse block on LF fender. Owners manual rather confusing and GM forgot to drop in the fuse when the truck was wired with towing package at the factory.