So here is where I'm at with this now. Took me a while to get back to it. I have a 2003 Ram 2500 5.9 cummins. All rear lights on the truck work fine. Problem is trailer rear lights. Started as left turn signal was out but all brake lights worked. Go to the fuse box and you could hear the relay clicking with the right turn signal but no clicking with the left turn signal. I am a electronics/electrical tech so tearing apart the fuse box and determining the relay to be bad was simple enough. i changed all three relays that are soldered into the PCB. Re-coated the PCB with waterproofing and reassembled. Now both turn signals work but the right brake light does not. I'm pretty sure the brake lights work thru the same relays. Relays are energized continuous to energize brake lights. Relay is pulsed to make turn signal flash. This makes both these situations odd that each time I had one or the other not working. Thoughts?