Ok i got a 94 5 speed pickup with a 3.4 swap. Ive done the side marker/turn signal swap where you put the turn signals up in the side markers but i did it a long time ago and it was working fine. I also have a light bar in the back under the tail gate with both turn and brake and reverse lights on it. I have trailer wiring on it also and it worked fine.

Recently i have encountered a problem. When i hit the brakes the right (passenger) turn signal lights come on with the brake lights. If i turn the right turn signal on and hit the brakes the turn signal stops flashing. The front turn signal even comes on.

The left side is completely unaffected. It works as it should. Along with all the other lights.

It doesnt matter if the headlights are on or not.

Ive looked at the passenger lights (brakes, turn signals, marker lights, and tail lights) and found no wires rubbed together. And i checked the trailer wiring kit. I tore about the passenger kick panel and checked the wiring there and i traced the wiring down the passenger side and under the passenger seat with no issues found. I redid the grounds by the fuse box by the driver kick panel. I tore apart the dash and checked the wiring for the brake switch (visually) and didnt see any obvious problems in the dash wiring. (I was rushed and did as much as i could).

I have no idea what to check now. It only the right side so i havent checked any driver side stuff.

Any ideas? Thanks travis.

If you have a trailer wiring connector check that 1st. You have a diode isolated system and there might be a bad diode leaking current. If not ,you could have a bad bulb or socket . Good luck!

X2 on the bad bulb or socket. I had exactly the same problem on, of all things, my Dodge pickup that I'm restoring. Check those bulbs!!!

My trailer wiring is added on. So how would i check it? And could it be a socket in the front lights or would it be in the back only?

If your trailer wiring is one of those plug in jobs from auto zone or oriellys unplug it to by pass it and see if that cures your problem. I had one of those on my old 90 and when I turned on the turn signal it would light the brake lights.........

i don know where its from but its spliced into the truck wiring harness all over in the back. i used to have a 7 pin trailer plug with the trailer brake controller. i deleted the brake controller and switched to a 4 pin plug since my 7 pin had a short. i did that a long time ago and it was working fine.

ill cut all ires going to the trailer wiring kit thing and see if that helps. i hardly ever use it anyway. have 2 times in 2 years.

Yep it was the trailer wiring. Cut the wiring and it went back to normal.