21 replies to this topic

[Rogue Leader]

My truck as mentioned in my sig is a 96 GMC 2500 ext cab 8 foot bed with the towing package. Did that come with a factory trailer plug or is that one on my bumper likely to be one that someone installed on their own?

I'm considering a trailer brake controller and wish there was a plug and play one. Yes I am lazy after all the work I had to do on this truck so far.

[ChevyTech77]

Your truck came with fused circuits that were blunt cut and taped to the wiring harness up above the spare tire for all trailer lighting functions. The trailer brake and battery charge wires are also back there but not fused unless you connect them up to the correct locations on the underhood fuse center and install the necessary fuses. All you then had to do was wire those circuits to a trailer connector of your choice, mount said connector to the bumper, and then connect the trailer brake wiring, up under the brake master cylinder under the hood, to the brake controller of your choice.

So yup, no plug and play. Pretty simple to hook up though because at least all of the wire is there, you just have to hook it up.

Edited by ChevyTech77, 28 March 2012 - 01:59 PM.

[Rogue Leader]

Thanks man, that was tremendously helpful. Gonna purchase one in the next few weeks.

[Rogue Leader]

Ok so this didnt go as well as planned. The connector that was on the truck did not work. The best I could get from it was to get the taillights to flicker for a moment. After dissection this is what I saw:



So I started to put a new one in. My problem, I don't have what color goes to what, and the old one was useles as there were no markings on it as to what was what.



So these even look familiar or is it possible (likely) that someone just stuck whatever wire in there to get it working.

I tried using a multi meter to test the wires to see if they work and I got nothing. Are they like ground triggered or something? I know that at least 1 worked at some point since I got the trailer lights to flicker.

[TimmyG]

Well one should flash witg the right turnsignal, one should flash with left, one running, one brake light. Etrailer online has the diagram showing what wire should go where. But 1st step would be to test and label all of those wires

[TimmyG]

Here ya go
http://www.etrailer....faq-wiring.aspx

[Rogue Leader]

Here ya go
http://www.etrailer....faq-wiring.aspx

Thanks man.

Only problem is I think I am gonna have a lot of testing to do if thats the case. I believe the middle of the plug is ground (right?), and from the wires that I have, the light green wire was the one hooked to ground (but that chart shows it as black or purple). And of course you can see many of the rest of my colors just don't match up. The large black and white wires on top were in a different grouping than the rest so maybe they are somehow significant.

Edited by Rogue Leader, 02 April 2012 - 07:54 AM.

[TimmyG]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change.
Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

[elcamino]

The six

-wire harness contains the following trailer circuits:
Yellow: Left Stop/Turn Signal


Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground

Light Green: Back-up Lamps

Light Blue: Center High-Mounted

Stoplamp (CHMSL)


The eight

-wire harness contains the following

trailer circuits:




Yellow: Left Stop/Turn Signal




Dark Green: Right Stop/Turn Signal




Brown: Taillamps




White: Ground




Light Green: Back-up Lamps




Light Blue: CHMSL




Red: Battery Feed




Dark Blue: Trailer Brake

[Rogue Leader]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change. Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

Ok cool, did not realize that about the brake wire. So how do the brakes work if you don't have a controller? Which circuit runs them?

[Rogue Leader]

The six -wire harness contains the following trailer circuits: Yellow: Left Stop/Turn Signal
Dark Green: Right Stop/Turn Signal
Brown: Taillamps
White: Ground
Light Green: Back-up Lamps
Light Blue: Center High-Mounted Stoplamp (CHMSL)
The eight -wire harness contains the following trailer circuits:

Yellow: Left Stop/Turn Signal

Dark Green: Right Stop/Turn Signal

Brown: Taillamps

White: Ground

Light Green: Back-up Lamps

Light Blue: CHMSL

Red: Battery Feed

Dark Blue: Trailer Brake

Ok based on this I think the thick black and white wires on mine at the top are battery feed and trailer brake respectively. Under hood theres a seperate fused line off the fuse box going to a thick black wire which i would assume is that.

I was wrong on light green being hooked to ground, it was in the center which was correct.

Edited by Rogue Leader, 02 April 2012 - 08:23 AM.

[Rogue Leader]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change. Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

Ok cool, did not realize that about the brake wire. So how do the brakes work if you don't have a controller? Which circuit runs them?

Just wanted to ask this question again. So the trailer brake wire doesn't work without a controller? If I don't have one how do the brakes actuate then?

[TimmyG]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change. Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

Ok cool, did not realize that about the brake wire. So how do the brakes work if you don't have a controller? Which circuit runs them?

Just wanted to ask this question again. So the trailer brake wire doesn't work without a controller? If I don't have one how do the brakes actuate then?

with out a controller they wont!

[ChevyTech77]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change. Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

Ok cool, did not realize that about the brake wire. So how do the brakes work if you don't have a controller? Which circuit runs them?

Just wanted to ask this question again. So the trailer brake wire doesn't work without a controller? If I don't have one how do the brakes actuate then?

with out a controller they wont!

Unless you accidentlly hook the battery charge wire to the terminal for the trailer brake, in the plug while you're hooking it up, and the charge wire is already wired to be hot. Then, the trailer brakes are just locked on all the time when the trailer is plugged into the truck. Don't aske me how I know this.

[Rogue Leader]

Skip colors, test and label each wire u have. And go from there. I read somewere while most people use those wire colors, there not set in stone and can change. Find a helper to sit in the truck with the key on. Sort out each wire. The 12v probbly wont be live, and the trailer brake wire wont work with out a controller but should be easyer once sorted out.

Ok cool, did not realize that about the brake wire. So how do the brakes work if you don't have a controller? Which circuit runs them?

Just wanted to ask this question again. So the trailer brake wire doesn't work without a controller? If I don't have one how do the brakes actuate then?

with out a controller they wont!

Unless you accidentlly hook the battery charge wire to the terminal for the trailer brake, in the plug while you're hooking it up, and the charge wire is already wired to be hot. Then, the trailer brakes are just locked on all the time when the trailer is plugged into the truck. Don't aske me how I know this.

LOL ok so now I am confused.

This plug should work without an aftermarket brake controller right? I mean not everyone has a brake controller installed yet tows trailers. So the opposite ends of these two wires are hooked to power and ? (in regards to factory wiring of course)

If I wire this up and press the brakes the brake wire should light up, right? Where is this connected to?