Struggling

jt metal · January 14, 2017

2006 GMC 2500hd with factory dual batteries. I can't seem to get 12v from 7pole harness, to charge trailer battery and interior lights?

Found the blank fuse under hood and replaced with 30a. Still no power at trailer harness. Checked with 12v tester.

Please help......

2017HD · January 15, 2017

On my 07 you needed to attach the orange wire found in a nearby harness to the post on the relay box in addition to adding the fuse I think for 06 the same thing is required - BTW the orange wire is close to the blue wire used for the trailer brakes. When they added the ITBC in 07 the blue wire was hooked up at the factory. For 06 they had a connector that attached to the inside fuse box and went to the aftermarket controllers.

jt metal · January 15, 2017

So, is the orange wire in one of the looms? Because I didn't see any loose wires anywhere?

But it's near the underhood fuse box?

jt metal · January 15, 2017

2017HD · January 15, 2017

Mine was in a tape wrap - not a loom. I may have been off with the color - it may actually be a red/black and it should attach to Stud 1 through F70. The orange color was from earlier trucks. This time I looked at my electrical schematic book and found the different color.

jt metal · January 15, 2017

Man.....I couldn't find it.

2017HD · January 15, 2017

Is there a wire attached to stud 1? is it red and black? if so then there is a problem somewhere else. On my 07HD the wire was flat cut - I added the ring, and fuse to make it all work. It looks like you might have the wire hooked up, can't tell for sure from your photo but it looks like some red wires on the far studs. Yours is a HD right?

jt metal · January 15, 2017

I have a red wire at both post 1 & 2. I'm starting to agree. Possibly a problem down river. This guy makes it look easy. Lol! I'm not having the same luck.

jt metal · January 15, 2017

2017HD · January 16, 2017

He also has an aftermarket wiring set up. The GM one is up in the bumper next to the lic plate. Not that that makes a difference in where the wires go under the hood. Now do you have the GM integrated brake controller or are you using an aftermarket one? Both of the wires on stud 1 and 2 are Red and Black in color, one goes to the brake controller (aftermarket) the other goes to the batt connector on the trailer connector. I have the integrated controller. I don't remember how I told the two wires apart - I did find the right one and hooked it up. Unfortunately this was several years ago now and I can't get to my truck right now to look further.

jt metal · January 16, 2017

The factory 7prong was involved in a fender bender. So I mounted a new one to the bumper. It was a plug and play.

I suppose I could disconnect at harness and check that for power.

I just keep assuming I'm missing something under hood. Especially after dummy.....

It has a taped up brake controller harness in the glove box. And I found the plug in for that under dash.

I was thinking maybe there's something under dash? GM has not been consistent with what to do, over the years.

2017HD · January 17, 2017

Things probably changed a lot from the 06 to my 07 new body style. Yes prior to the integrated brake controller, they provided a connector between a plug inside the cab, to cut wires. Some aftermarket brake controllers also provided a similar cable. My last brake controller install was in 05 on my 99 Tahoe - replaced an older unit I had had since 89 - and now that I think about it, the RV store did a free install on that one.

Back to your 12V charge ckt issue. You could have either the red/black or solid orange wire - I don't have wiring info for the 06 models. I do know that in both 89 and 99 the Orange/Blue was the right color code where the blue wire came from the rear trailer plug and needed to be fed into the cab and to the output of the controller. The orange was attached to the fuse/relay box and provided the 12V charge ckt. Beyond that I suspect that like my 07, thre is another set of connectors out of the frame loom that go to the actual connector - on mine it goes to the integrated brake controller on the frame rail and then to the trailer plug.

If your old connector was damaged and you added one under the bumper, are you sure that damage was not done elsewhere?

jt metal · January 17, 2017

HD2007, idk??? Racked my brains out. Stopped at an r.v. place today. Two guys jumped into action it the packing lot. Started peeling things apart, and came to the same conclusion. I've got a break somewhere between post at box and connection to 7pin. Box is already wired, which I kinda thought. And they found no power at rear of truck b4 7pin. No corrosion between harness that leads to 7pin, or power.

I still think something is just not connected. But they couldn't go any further without making an appointment. So that's what I did.

They will get to the bottom of this with no b.s. story. If it's a connector, they will explain.

At this point, I'm thinking it's an under dash connector, but that's just a guess.

jt metal · January 20, 2017

OK, so this did not go good. From the factory that wore is connected to post #1 or b+. I've did what I could do. I have remote start that is sharing same post. Which thru me cause I have power at both terminals on fuse. I assume the remote start is back feeding power for it to work.

Switch to post #2. Same. No power to rear.

Friend shows up with exact same truck. We open the hood, put 30amp fuse in and he has power to top right terminal. Where I don't.

So, it's down to chasing a problem or running a new wire.

I hate!!!!! Butchering a new wire in!!!!! But I don't see this ending any other way!

Joe