LCM problem, Help

My 04 is saying check LCM....all lights on tractor work except dash. Now on the trailer I have marker lights at top all over Trlr....I have no marker lights on bottom of Trlr. If I turn on blinkers they work and brake lights work. All fuses are good. Ant thoughts or suggestions?

 

Pablo i could really use a diagram

 

There is a connector under the cab ....
Follor the cable ftom the trailerconnector in the back

 

I was having similar problems on two different trailers with the same truck and both times it was the trailer socket. There was a short (about 2 ft long) adapter from the socket to the wiring harness and both times in my case they (the adapter) were the problem.

 

Which relay was it. And what is its exact location. I have 2007 with identical problems .

 

Hello did you figure out the problem? I’m having trouble with the same problem?

 

Hey man did you figure out what was wrong? I’m having the same problem and can’t figure it out..