Help: How to disconnect trailer wiring harness

I'm trying to isolate a potential short in my wiring job I did into the trailer wiring harness.

To sanity check myself I'd like to disconnect the trailer wiring harness from wherever it inputs to the front of the truck so I know that it is in fact an issue in the back.

Anyone know how to completely disconnect the trailer wiring harness?

 

Under the bed there is a connector. Trace the trailer wire. Look around the spare tire.

 

Much appreciated

 

U r S.O.L.
3rd Gen has no splices/connectors from bumper to engine bay. 2nd Gen does.

 

Doesn't mean I can't fix it

 

Of course not...

 

What are the signs of your potential short?

 

OP, listen to this guy as he knows what he speaks.

 

The 10A fuse to my STOP circuit keeps blowing, preventing me from either A.) Starting my truck, or B.) getting out of Park once it's started.

I've got a KC rear tail light bar and a BD RTL-M spliced into my trailer harness, which seems like the best place to start looking. If I can disconnect the trailer harness then I have a good reason to go and inspect the splice-job for problems.

 

What's the amps required for the KC bar?

 

1.) I've had it working fine for a couple of years now, so whatever the amperage requirements are of it shouldn't be an issue. Docs say 5A max though
2.) I have the power connections for both bars hooked up to the 12v line (non-signal). This is where I'm not sure about the design. I wouldn't imagine the 12v power line for the trailer harness would be an issue because that's the same power line that would provide any sort of accessory power to the trailer.

I imagine there's probably a short from the 12v power line to one of the signal lines.

 

So these added light bars require separate power and signal inputs, correct?

 

Correct, they get power, and then the signal lines just open the gates for voltage to be applied to the appropriate light.

 

The issue I see, maybe it took time to manifest, is that the towing STOP is tied to TURN. So maybe the added light(s) controller(s) has failed.

 

My T-tap splices are pretty shit, and the whole bundle of wires is a super exposed rats-nest, on top of that I live in an area with super salty ocean air. There's like 30 possible modes of failure here.

If I can remove the entire wiring bundle I'll just rebuild it with sturdier connections. I would have done that originally if I took the time to just trace the harness up to a connection point LOL.

 

Why not remove the added lights and verify the spliced area for failure/rust, etc?

 

Well, if unplugging the trailer harness ends up being brain-dead easy, then I'll do that first to verify that the issue is with the harness.

If that alleviates the symptom then I'll dive deeper. Probably end up overhauling it anyways, but I'd rather do the thing that requires the least effort first.

I'll take a pic of my rear end situation tomorrow so you have an idea of what I'm working with. I guarantee you haven't seen anything like this before.

 

Any progress?

 

@caribe makaira

You were correct - no trailer harness disconnect. I unplugged the 30A trailer power fuse and it started up and I could drive it around but the STOP fuse ended up blowing again. Gonna try pulling the 7.5A fuse for the trailer brake wiring that's in the cab and see if that resolves it.

If not then I'll just unplug all my rear lighting and see if that fixes it.

I also noticed that when I engage my left blinker, it flashes once and then shuts off......I'm thinking this could be a clue....