Trying to pinpoint towing, wiring issue

I just hooked up a trailer to my 17', using the round plug (not the straight 4-pin). The brakes on the trailer activated, only way to tow it is unplugged.

I also put a Kenwood aftermarket GPS in my dash, did the wiring myself (everything works great, until now). could I have messed up wiring somehow with that? Or could the trailer wiring be different than the plug? (it's a really old trailer - probably 15 years at least).

 

First question, does your truck has a trailer brake module installed?
Second question, do all of the trailer lights work properly?
Third question, do you have a multimeter or 12 volt test light?
Trouble shooting would be a pain without a meter or light.

 

I would say your trailer plug is wrong it prob matches a custom job in and 80s truck where it was still all diy wiring.
It prob caused you to blow a fuse unplug trailer replace dude. Get test light and the diagrams for your style plug from Google test truck 1st then rewire trailer to standard wiring aka the diagram.

 

This. It ain't your tacos fault

 

1) Yes - the truck has the factory tow package. I've towed successfully using the 4-pin, this was the first time using the round plug.
2) The trailer lights/brakes do work properly - oddly, when using the trailer with an old chevy, the trailer works as expected (same round plug).
3) I believe i do (would have to hunt it down)

 

I should have added, I also have an older silverado and the trailer works as expected with it. No blown fuses, all lights work (when plugged into the silverado, not the tacoma).

 

Your wiring should look like this. Anything different won't work.

 

Don't make any wiring changes to the Truck. I bet that the red and blue on the trailer plug are reversed.

 

If you find the meter or test light check out the diagram in post #7, once you check the truck plug on to the trailer plug. Very slim chance that it's the truck plug but stranger things have happened!

 

99 percent chance it is the trailer plug wiring.

 

Yup! It's weird that he says it works on the Chevy but it could be that both the Chevy and the trailer are wired wrong.

 

The guy who owned the Chevy probably installed his own trailer connector on his truck. Then matched his trailer to how he wired his Truck.

 

Go to etrailer.com for good wiring diagrams.

You will also find that travel trailers, (which is what most of us wire our trucks up for) are wired differently than farm or utility trailers. I'm thinking you just need to swap some wires around on the trailer.