Trailer Harness Wiring Issues

[Kyle E]

Hi all,

I installed a 7 way trailer harness on my 84 K10 and am having issues with the trailer lights.

With no trailer hooked up, all of my lights work properly (turn signals, brake lights, etc)

With a trailer hooked up and my truck lights off, my blinkers brakelights, everything work properly on both the truck and trailer.

When my truck lights are on, my brake lights work fine on truck and trailer but when I turn my blinker on either direction, all of the lights on the trailer flash and both my truck blinkers flash and I cannot figure out why.

I used a harness from O Reillys to splice into the existing wiring for my tailights turn signals etc.

Any suggestions would be helpful.

Thanks in advance.

 

[Snoots]

Can't suggest anything without seeing what schematic came with the harness you got and what color wires you hooked into.

 

[Charlie]

 

[bucket]

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I stole these from the e-trailer website

 

[Kyle E]

Thank you for the responses. I will see what I can pin out on the Harness and send pictures of the harness and splices on Friday.

Kyle

 

[Jrgunn5150]

I would suspect a bad ground or connection at the trailer lights.

 

[Kyle E]

I attached images of most of the wiring. This is the harness from O Reilly. This plug on this plugs directly into the 7 way. I bypassed the 7 way and plugged this straight into the utility trailer with the same results. The tailight connection isn’t pictured. It just has the truck wiring, license plate lights, and trailer taillights wired together.

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[gmachinz]

Something is odd here....you appear to have the trailer white ground wire spliced to the truck wiring light green wire which is +12V for your reverse bulbs...

 

[gmachinz]

And most 7-round connectors have a red wire which is typically a turn signal wire as well-at least the Pollak kits I stock are that way-and the large 10ga black is usually battery +12V while the white is chassis ground....so its a bit odd on their universal color coding I’ll admit lol

 

[Kyle E]

I agree the ground doesn’t make a lot of sense. I tried it wired directly to the frame and both light green wired straight to each other with the same result...

 

[HotRodPC]

I know it sounds strange, but I'm with JR and it being a ground also. It might be the lights on the trailer aren't ground good through thick or heavy paint even. Grounds at all lights and all wires have to be very good or it'll seek ground from something else and cause these issues your talking about. Like those times when you see people with taillights on, then they hit a turn signal and the tail light on the other side goes out every time the turn signal filament come on on the other side. I know for a fact that's bad grounds when that happens. Been there done it and seen that several times.

 

[Snoots]

I've seen WAY too many trailer lights not operate properly because the ground was only through a screw. The terminal was sitting on top of paint! Yes, there IS a ground; but not enough of one to help carry a return for several amps.
Also seen a lot of people wire them thinking that, "It'll ground thru the hitch."
Sure signs of Anal-Cranial Inversion.

 

[HotRodPC]

I've seen WAY too many trailer lights not operate properly because the ground was only through a screw. The terminal was sitting on top of paint! Yes, there IS a ground; but not enough of one to help carry a return for several amps.
Also seen a lot of people wire them thinking that, "It'll ground thru the hitch."
Sure signs of Anal-Cranial Inversion.

Absolutely. And everyone seem to get stuck right there at the nose of the trailer and the truck harness. They forget about going back there to the trailer lights themselves that self ground to the trailer chassis as they are bolted on to that heavy paint.

 

[HotRodPC]

You could also go to a buddy or someone you might know that has a known working trailer light set up on their trailer, plug it into your truck and see what happens. If their known good trailer light set up works, then you know it's your trailer wiring. If not, then you know it's your truck wiring. I won't bet the family farm on it, but I'll lean heavy to the problem being grounds.

 

[Jrgunn5150]

I like to ground the lights at the lights, just because.