Trailer lights wiring

Reply Subscribe

Thread Tools

Search this Thread

Oct 2, 2011 | 04:21 PM

dethomson

Thread Starter

Tuned

Joined: May 2008

Posts: 334

Likes: 41

Trailer lights wiring

I thought I'd post this here since the question is specific to dent sides.

My truck has the high end wiring harness and all from a '79 camper special SC 4x4. I seem to be missing something though.

Question: What OEM parts are missing from my picture so I can get power to my trailer lights? I'm guessing I misplaced a relay when I was rebuilding everything. I know I can throw an aftermarket relay in there, but like to stay factory when possible.

Does anyone have an idea of what's missing?

Oct 3, 2011 | 05:04 PM

dethomson

Thread Starter

Tuned

Joined: May 2008

Posts: 334

Likes: 41

I have always thought the black male connector must fit the the black female connector (at the top of the picture), but nothing ever came of connecting the two. I turns out, while I was in my dash today, I had disconnected what I think was the seat belt buzzer. I thought, lets connect it and see it is my missing relay for the trailer lights. I The seat belt doesn't buzz and I now have my trailer light connection working. We'll leave this one as an ID 10 T error.

I'm still curious what those other two connectors are for. I'll have to see if I can track them down in my wiring diagrams.

Oct 3, 2011 | 07:14 PM

old rat

Junior User

Joined: Aug 2011

Posts: 54

Likes: 0

Go to the rear of the truck and find the wire going to your license plate light. Follow it to the plug (probably 4 way) and that should be for all your rear lights. That harness probably runs side to side along the rear frame with the connector towards the drivers side. Either splice into those wires or get a trailer connector that plugs into it. Just did my 77 a few days ago.

Oct 3, 2011 | 07:40 PM

dethomson

Thread Starter

Tuned

Joined: May 2008

Posts: 334

Likes: 41

Thanks for responding. I have my original question figured out and am good now thanks. I do find it odd though...the feed wire coming out of the factory relay is half the size of the camper special trailer wire harness. There's not much load from the lights on my car trailer, so I guess I'm good for now. An upgrade might be good in the future if I start towing something with a bunch more lights on it.

Working on these old trucks is cool because all the wiring is so simple. I have the factory service manuals (or they look like them) and they include the wiring schematic - which is on 9 pages AND shows all the plug shapes and stuff. It sure makes figuring things out easier. I should have looked at these before asking my question.

Now I'm looking at how the factory provided connections for a trailer brake controller. I have mine wired up, but it's not connected to power source through a relay and can drain the battery if I leave it connected. The wiring scheme shows the brake controller connections, so I might track them down and see if they are worth using.....

Oct 3, 2011 | 08:21 PM

hasteranger

Lead Driver

Joined: Mar 2010

Posts: 5,250

Likes: 10

From: West Virginia

all factory trailer brakes work with the ignition off... my 04 ex is the same way. I think its in case your ignition got shorted out or shut off, you would still have trailer brakes if the truck was rolling and you needed to stop.

Oct 4, 2011 | 06:41 AM

dethomson

Thread Starter

Tuned

Joined: May 2008

Posts: 334

Likes: 41

good point. i'll need to make an accessory power block that i can power off when it's not needed. this is the only thing on my truck that could be draining my battery.