Hi everybody, I'm having a problem with my trailer lights that I'm hoping someone can shed some light on. I have an 03 Ram with factory trailer wiring. My trailer uses a 4-pin connector and the Left Turn Signal and Left Brake Light on the trailer is not working (Left Parking Lamp, Right Parking Lamp, Right Turn Signal, and Right Brake Light are fine on trailer). All parking, brake, and turn lights are working normally on the truck.

I've used a voltmeter to check the 7-pin and 4-pin connections on the truck and determined that the problem is definately on the truck and not on the trailer. It had been working fine for 4 years previously so I know that the wiring scheme is correct. I also checked the trailer-left-turn wire (yellow-pink) at the wiring harness that is under the truck just behind the left front tire and I do not get a signal there either.

The fuse for the trailer left turn signal (#46) is fine. The service manual shows a trailer left turn relay and a trailer right turn relay but I don't know where they're located, they're not listed on my fuse panel. Does anybody have any ideas on how to further trouble-shoot this? I'm guessing it might be the trailer left turn relay but I don't which one it is. Would a bad turn signal realy cause the brake lights not to work since the trailer is only using a 4-pin connection?

 

The bulbs on the trailers are typically dual filament. If the stop/turn filament is burned out, you'll get the problems your noting. I'd start by taking the bulb out, cleaning the socket and replacing with a new bulb.

If you have a voltmeter, you can check the voltage for the running light, left turn/stop, and right turn/stop signal. But it sounds like it is a bulb. If it is, go ahead and replace both of them.

Never mind, just reread you post, go here for a copy of the repair manual.

 

Thanks, I already have a copy of the manual. The factory trailer wire's have a yellow-pink wire (left-side stop and turn) and a white-pink wire (right-side stop and turn) that run all the way up to the engine compartment. These are completely seperate from the other stop/turn signal wires for the trucks. I know I can cut the yellow-pink wire and splice into the left stop/turn wire for the truck. This will "fix" the problem. I was just hoping to find the real problem so I could fix it the right way.

I'm just stuck... [sm=violin.gif]

 

This is the same exact problem I'm having...did you ever find a cure or did you end up splicing into the rear light?