The Diesel Stop banner

Trailer? wiring pinout

2K views 8 replies 4 participants last post by  MPD56 
#1 ·
Does anyone have the pinout and wiring for the 2 plugs near the trailer hitch wiring. And not the trailer hitch wiring. I have looked at the chassis builder pages but that shows a 4 pin with 3 wires and a 4 pin with 4 wires near the correct location. But most of that is for the E series. I have a 2 pin plug with 2 wires (White and Blue) and a 6 pin plug with what looks like 5 wires. The White and Blue wire look to be about 10ga and I am guessing they are Com or Gnd and Brake controller. The 6 pin wires look to be about 16 to 20ga and are multi-colored. So I am guessing thay are the lights for the trailer. I would like to be sure. I am adding 2 LED worklights in the bumper that will go on in when in reverse or from one of the upfitter switches. So I'll be mounting 2 relays to accomplish that but I need a feed from the reverse light wire to drive one of the relays and would rather not "T" off of the trailer harness, although I may have to do that to get a constant 12V for the relay output.
 
#2 ·
And not the trailer hitch wiring
You're sure it's not the trailer connection? Any trailer lights or brake controller signal would go through those. If it's not that, I have no idea. Have a picture?
 
#3 ·
The cover of the 7 pin has the contacts labels either on it or inside it.

Grab a voltmeter or test light and check the truck. This you will find the problem is the trailer.
 
#4 ·
I love having this conversation with the dudes at U-Haul....
 
#5 ·
these are the 2 connectors. As far as i know the 7 pin works. (camping season was over by the time I got this truck). But if you look at the "body builders layout book" pg 12 & 13 they have connectors that look similar....but not quite what I have. Also on a related note I found what i thought were the 4 blunt cut wires for the aux switches. Behind the fuse box on the drivers side by the firewall. My colors don't match the dwg, but I am in field service and am used to the colors not matching the drawing. I took the shrink wrap off 1 and put as butt splice connector on and went through the switches 1 at a time with the key in acc. It never had voltage. So I started the engine. Same deal. I can put my ear near the drivers side dash and hear a relay click for every switch. Here are my wire colors: white, brown/white, gray/ornge, white/orn. Is there somewhere else that I should be looking for the wires from the switches?
 

Attachments

#6 ·
So I found the other ends of the 4 wires that were taped off in the engine compartment. They were in the bundle with PTO stuff under the dash. I pulled back the wheel well liner and spent about 1 1/2 hrs looking up at the wiring. There are no other blunt cut, taped up wires. So its 75 now and this time tomorrow it will be 40 or less. I got other things to do. Still don't know what the two other connectors are for. Oh well.
 
#7 ·
Sorry but what year is the truck.

Are the pictures of those connectors by the left rear wheel well.
 
#8 ·
2015. The connectors are inside the frame by the spare tire. I pushed them out so I could look at them. The 6 pin connector wires seem to match up with the signals in the 7 pin Trailer plug. I have checked the wire that is the BU lights and it goes high when I put the truck in Reverse. The orange wire goes hi when the key is in ACC position. On the 2 pin connector I did a continuity check between the Gnd of the trailer plugs and the white wire of the 2 pin connector and they are connected. So that's where I am going to tie in for the reverse input to my relay and also the gnds. I just got some 18/3 cable that I'll run from the firewall to the back. I will bring power and 2 of the aux switches. I will go to the other relay to fire the aux backup lights (when I'm not in reverse) and the other switch will be for when I get some LED bedlights. The one thing i was confused about (other than the purpose of those 2 connectors) was that I thought the AUX switch wires were in the engine compartment. I now know that they are in the cab and need to be tied to the 4 pass thru wires. So hopefully by the end of the week I will have the aux reverse light wired up
 
#9 ·
Thanks for clearing things up.

It looks like you found what you're looking for.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top