When the trailer is hooked up to the truck. I have no running lights or tail lights. The turn signals and brake light work. This happens on both horse and travel trailer. I am not good at electrical so not sure where to start.

 

check your fuses. one of your trailers more than likely has an open short.

 

Run a separate ground wire from the truck to the trailer.

 

minet just started doing the same thing im assumming i have no power to tail ligts. If it was a grounding problem why would the brakes and signals work?

 

If the tail lights on the truck are still working than the wire to the back is okay. Although I have not experienced it the general consensus is our light switch and wiring are terrible. The general consensus seems to be to put relays at the back of the truck to handle the load of your trailer.
If you start at your trailer plug on the back of the truck with a test light check that you're getting output on the appropriate pins. If you are that you need to go to your trailer.
I would start with a battery charger or some other 12 source of electricity and apply power to each pin one of the time and make sure that the appropriate lights work. The color code is; White is ground, blue or breaks, Brown is your trailer clearance lights, black is generally 12 V positive all the time, yellow left turn, greed is right turn, and orange and auxiliary wire. This is for seven pin plug. I don't know with a six pin is but I believe it's the same minus the auxiliary wire. A flat four are; White is a ground, Brown is clearance and taillights, yellow left turn, green right turn. I hope this helps.

 

I have an APP for that!
No i have access to a TowDoctor. You can test all the lights and brakes on the trailer one at a time to find faults.
Now i have found that 90% of every trailer light problem is loss of ground.

 

I had that problem on my '06 before. That is, no trailer lights - truck lights were fine. I read about it on this forum and found out it was something that the dealer has to reset. I took it to the dealer and the problems was solved in about 5 minutes. Also, they were king enough not to charge me. No problem since.
Check this link: http://dodgeram.info/tsb/2006/08-021-06.htm

PCM

 

Mine was the ground. I couldnt understand it because my blinkers and tail lights still worked? Replaced the rusted bolts the held the ground wire down and it worked

 

Travis, start by checking the fuses located under the hood. When you remove the cover from the fuse box there should be a label on it telling you what each fuse does. IIRC the fuses are the micro type.