Okay, this is probably something really simple but I wasted 2 hours today trying to figure this out. The problem I had starting the day was that my left trailer light was out. I have a motorcycle trailer that I connect to my truck also, and that left light was out, so I figured that the problem was with my truck wiring harness. The 4 prong harness, which I cut off today,is on a 2003 Dodge 1500. The colors coming from the truck are white (with small red stripe), yellow (with small red stripe), black (with small red stripe), and a plain black wire which is larger than the other 3. I can't find a wiring harness picture to tell me what those 2 black wires are. Can you tell me.

The 4 prong I put on today has a brown, yellow, white, and green, none of them are larger than the other. But when I plug it up to match the trailer which is white, green, yellow and brown, the lights on the trailer come on, but I can't use my signals on either side. What am I doing wrong? Is it that one of the colors is not larger than the others?

brown goes to tail lights/parklamps
yellow goes to left turn
green goes to right turn
white is the ground.

I tried that but something about those 2 original black wires is not working with the new harness I put on today. Why is one of the black wires 2x's as large at the others?

do you have a test light that you can go back to the harness and test which wires do what with,im not that familiar with dodge's color codes on there schematics,but if you have a test light you can turn each blinker on and find which color goes to what side that way,and the park lamps will come on steady light when they are turned on without the headlights.on the chevrolet the black wire is 12v lead for charging.im not sure on dodge.

also the newer trucks have a fuse for the trailer wiring under the hood that should be marked left turn/right turn/park lamp

Thank you I will check that. Preesh

if you cant figure it out i will be coming through Garland tommorow afternoon around 3pm so call me i will be glad to stop by and check it out for you.214-538-9071 cell

I am probably gonna stop over at Dodge and pick up another harness...I prefer OEM anyway...I just wanna get it done before I got to Toledo Bend on Thursday, but I appreciate the offer!!!! Thanks so much. We actually got the keel guard, brush guard, and new Humminbird 585c on today, so I guess I did get something accomplished!!!! ahahahahaha

no problem.