I finally fix the problem.
Problem: No power (connection between the back of the central fuse box through the firewall to the Aux fuse box that holds the trailer relays. There must be an interruption in the wire between the two. The strange thing is, I was measuring around 8 volts at the relay (input side). I check for continuity from the back side of the central fuse box out to the Aux fuse box, with no continuity.
To confirm the problem, I ran a jumper from the battery to the relay to give it a full 12 volts, and then the trailer lights worked. I then pulled the electrical tape back from underneath the Aux fuse box about 6 inches until I ran into the wire split connection (where one wire from the main fuse box splits into two wire for the RH and LH relays). I cut the wire at this point and added a 20 amp in-line fuse. From the added fuse, I then ran a wire across the front of the truck (on top of the radiator) to the positive side of the battery.
My trailer lights now work.

Thanks for all of the help.

Jeff

 

Sounds like corrosion in the big plugs at the firewall below the master cylinder. Be prepared for another circuit to give trouble. If it does, you should pull the two big plugs apart and clean up any corrosion, then use dielectric grease on the pins when reinstalling.

 

Scuba, Can you get a pic of where this is? I thought I had check that wire, but from what you are describing, I didnt.

Thanks