Done all the checks on the obvious stuff but can find no reason why there appears to be no power to the right hand trailer brake/turn signal/flasher. All lights work on the 2006 3500 6 speed 4X4. Voltage reading on the tow harness connection left side is 12+, but right side is 10. 7 and shows no change when calling for the light. Left side shows 10. 7, but goes to 12+ when calling for the light. It isn't just one trailer doing it, all three trailers have the same right hand malfunction. All other lights on trailers function as they should. Help!