All trailer lights blink w/ one turn signal activated

Finally getting around to mounting a hitch to my 03. There was a 4 pin hanging out in the bed and I just grabbed a test 12v light to figure out which lead was what and I'm finding that with one (left or right) signal on, all the trailer lights are dimmed, and blinking (tail, left turn and right turn).

Is there any reason I couldn't just tap straight into the wiring at the tail of the truck? That would just end in an increased risk of popping a fuse?

 

Tacomas have a separate filament or led for turn signal and brake light. Tailers the turn signal flashes the brake light. You need a box that converts the Tacoma system to the trailer system, I got one at a parts store when I needed one.
Logically you need to XOR the turn signal and brake light on each side and sent that signal to the trailer brake/turn signal light.

 

Thanks, this was probably a stupid question. But thanks none the less.

 

Sounds like you have a short in that wiring. Is the 4 pin you are talking about OEM, or was it something someone wired in previously?

 

There is a wire leading from the fuse box all the way to that terminal at the end of the truck.

Very much not a factory job.

 

Just one wire? Do you know where the other 3 go, or do you mean all 4 going to the fuse box in a single loom?

 

Here a link to a Trailer Light Harness at eTrailer. Might be the safest thing to do. And maybe remove those other wires you found if you think they aren't original or you think they might have a short.

 

Just one goes to the box, I have no idea where the others go.

 

I bought the whole thing at e trailer and decided to pass on the harness at the time. I scrounged up a converter box from another toyota and will see if that clears up this for now. I hear now from multiple people that the whole filament separation is a thing.

 

Good luck man! This is probably why the Brake light on my Habitat flashes when my blinker is on

 

You need to sniff through the bible
https://www.tacomaworld.com/threads/the-tacoma-towing-bible.4031/

 

It's all fixed. I did indeed need a converter so brake and turn would share a filament. Got the 7 pin/4 pole bits all worked out. Whoever wired that 4 pole brought the hot side all the way from the battery on one of the poles, and grounded in the tail light fixture. I was cruising around with a hot connector in my bed the whole time. Even more bizarre, there was 3 (yes 3!) fuses wired into that one single line. Left and right signals were jumped together further up. Tore everything out and started over.