V2500 Trailer/Towing Wiring Questions...

[shiner2001]

I started rewiring the trailer wiring plug on my Suburban today since the housing on the old one was all cracked and ran into a couple spots where I figured I'd come to the experts for some quick assistance. I've only had the Suburban for a couple months, and I'm not super familiar with the factory options that might have come with it. I would assume that since it's a 3/4 ton, it would have come with a beefed up towing package (as far as the electronics). I don't know if the 7-way plug that I am replacing was factory or not, however, and as far as that goes, if the wiring that goes to that plug was factory, either. Here is a picture of what was wired into my old plug:

On the right is your typical 4 or 5 way wiring, on the left are the two heavy gauge wires that are the cause of my question. The red (with a hard-to-see blue and white tracer) and the blue wire are both hot, key on or key off. The white wire on the far right is never hot, even with brakes, lights, key, etc. I don't have a wiring diagram for this truck yet, so if anyone can help me out with these, that would be fantastic. Also, I am curious if my trailer brake controller is a factory option or if that was aftermarket. Here it is:

I have all of my standard trailer wires traced out with my meter (left, right, tail, brake and even the reverse light), but what I am stuck on are the brake controller and the acc wire for the 7-way. As always, any help is greatly appreciated!!

 

[ccarley]

Oh man this brings me back. I used to work at an RV shop...

Red = 12V hot, for charging battery on trailer
Blue = output from brake controller

The blue may not be wired correctly, if you are seeing 12V just sitting there. You should be able to see those wires around the firewall where the steering comes through.

The other wires.
White = ground
Yellow = left turn (I think)
Dark green = right turn (I think)
light green = backup
Brown = tail light (I think).

I could be mixed up on the right turn/tail light colors, it's been a while.

On the 7-way plug, the center pin is not ground, but backup lights.

Usually, the red wire under the hood should go to a circuit breaker or fuse that's attached to a +12V point that is near the top of the firewall, I want to say above the brake booster somewhere. It may or may not be covered, and there may be multiple wires coming off of it. The blue wire should go inside, to the blue wire on the brake controller. The brake controller should have a wire scotch-locked to the brake trigger wire near the switch on the brake pedal, and then a +12V wire as well as a -12V wire headed to a constant power source; generally a circuit breaker under the hood.

I doubt the Activator came from the Chevy factory in your Suburban, but it might have been a dealer installed option.

Good luck...
Clay

 

[shiner2001]

I went ahead and wired it all up to the new plug, just leaving out the blue wire. I terminated that and everything else is working fine. Might go back and dive into trailer brakes at a later date.

 

[dhcomp]

If you don't own a trailer with trailer brakes, and don't plan to tow one, yank the controller and cap the wires.

Thats what i did....

 

[shiner2001]

If you don't own a trailer with trailer brakes, and don't plan to tow one, yank the controller and cap the wires.

Thats what i did....

I have a couple that do, but even though this is a 3/4 ton, I'd still rather haul with my 5.3 probably, just for mileage. Just wanted it to all work since it was there. Depending on what it takes to repair, it can sit as it is now and I'm still good to go on a trailer with a 4 or 5 pin plug. And by the way dhcomp, I was just looking through some of your threads last night...love the Suburban!

 

[AJMBLAZER]

GM didn't sell them with a brake controller. They did offer an option to have the wiring all setup from the factory for one with a plug in the bumper and everything, but no controller was offered. Dealers might have sold that as an option but I don't know for sure.

The Blazer has the wiring package and an aftermarket brake controller but somewhere in the 20 years before I got it a home brew wiring whiz dinked with it and I have wires ending and hanging and others going nowhere. I don't use the 7 pin anyway but one day I'll probably need to do this just so I know it works.

 

[Silverbullet555]

I went ahead and wired it all up to the new plug, just leaving out the blue wire. I terminated that and everything else is working fine. Might go back and dive into trailer brakes at a later date.

It's not too bad. On my V20 I pulled out the trailer brake controller then 2 months later added electric trailer brakes to our trailer.

Anyway, I rewired the brake controller and it wasn't that hard. The red wire that is bonded to the blue wire connects to a 12v post up under the hood over the steering column. The blue wire would connect to the trailer brake controller blue output.