Trying to wire my truck for trailer brakes so I can haul my parts truck home 4 hours. I bought a 7 wire connector thinking it would just plug into my 4 wire lighting connector. Ha! Did 99s come wired from the factory with a 6 wire harness? I think mine might have and the connector was snipped off somewhere in it's life. How would that hook up to a 7 wire harness?

 

7 > 4

So your truck HAS a connector or its snipped?
Mine has 2 seperate plugs. I'ma go get my manual and see what each is and get back to you cuz i'm not sure.

 

You should be able to buy a 7 pin adapter from a parts store, dealer, or make one.
Do you have a diagram for your 7 pin stating what is what?

6 pin:
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

Was the 4-pin you have a rectangle or circle?

Edit: This site should help http://www.etrailer.com/faq-wiring.aspx

 

Was looking into this cuz i'm bored and may want to get trailer brakes later down the road. If you only have a 4 pin then the wires are tucked away in the loop up around the spare tire.

do you have a brake controller too? cuz i think you need one to run trailer brakes.

 

Holy crap dude, thanks a lot! My 4 pin connector is flat. 3 females, 1 male. It looks like there was a factory 6 wire connector but the end was cut off for some reason. The wires are still there. The place I'm planning on renting a trailer from has everything wired for 7 pin connectors. I have a brake controller, but it's not wired yet. Kinda contemplating maybe just renting a car dolly and towing it home sans brakes, but I suspect that might be dumb even with a little RCSS... In over my head here!

 

There was a page on how to wire the controller. seemed easy enough. I'll see if i can find it again.

Edit: http://www.etrailer.com/faq-cbc.aspx

between those 2 pages you should be able to wire everything up

 

Hmm, looking up a 99 Sierra it gives a bunch of products for trucks with or without the 7 wire harness. Maybe the 7th wire is a ground and all I need is the truck end of the connector???

 

no. if you look at that wire diagram between the 6 and 7 pin plugs you will see the difference. the Center on the 6 pin is 12v and the center on the 7 pin is auxilary and the 12v is pin 4 of the diagram.
I was reading a forum on a guy that ran the aux wire but i'm not sure where he ran it. Trying to find it again.

Edit: the Auxiliary you hook to the backup lights. Should be Light Green. When it goes into reverse the trailer brakes release completely so you don't have difficulty backing up to unload a boat or something.

 

When I wired mine up, there was a stock 4 pin and two other wires hidden in the harness. when I found the other wires I still had one pin left. well if you look at the diagram on the package there is one that is supposed to be an aux wire. I just ran a wire form the fuse box to that pin in the female harness i mounted to the truck. when i was working on the trailer, i put two lights inside to a switch to that same wire on the truck. It has power whenever the truck is on. Hope that helps. Mine is an 01 so it may be different though.

 

Did some more reading and that is how you should do it. It doesn't go to the reverse lights like the guy did in the thread I had read.
All 7 pin's are wired the same but the 6 pin's can have 2 wires swapped.

Thanks Camo