Ok so heres the deal. ALL of the blinkers and brake lights etc work great on my truck. When i plug in a trailer (and i have tried several different ones with the same result) The passenger side brake/signal light will not do anything. It will work as a running light and then the driver side running and brake light works fine. I measured it with a fluke and found that no voltage comes out of that lead while using brakes or signal on the truck. I have looked at the harness along the frame and can not find any damage or a possible broken wire. Does anyone know anything about this??

Also this is a 2004 4 Door Ram HEMI 4x4 is that matters....

 

If you have verified that the trailer wiring is not the issue, then I would pop off your brake light assembly and check the circuit board on it as many of them corrode.

 

Is that where the wiring splits off to go to the trailer plugs?

 

That's exactly what I have! Will have to check that out myself.

 

our trucks have different fuses for the trailer check those then check the grounds. weak grounds can do some funky stuff

 

I dont know if that's where it's spliced off of, but the ground must definately be. It sounds like a grounding issue.

Marx you must have beat me by a split second on the :59 sec count...lol

 

lol ya

 

The trailer only has one ground so why would only one of the lights do that? Then each light references the mounting point for its own ground. The running light portion of the right night works fine but no bright side for brake or signal. Then the left side light works in all forms.

 

Are all of the trailer light fuses in the fuse panel under the hood?

 

i had this same issue when i hooked up a trailer. do the all the lights work in the front. there is a fuse for both left side and right side lights in the fuse box and mine ended up blowing can't remember what fuse number it is or how many amps i will find out this weekend if it does it on a different trailer cause i have only pulled the one with my truck so far.