Trailer Running Lights Wire Color. I was running out the door when I read Brad's response. This is accomplished by tapping into the tow vehicle's electrical harness to transfer power to the trailer wiring system.
The trailers that never have lights issues are the trailers that I have redone the wiring on and ran a separate ground to every light. Got a brand new trailer and hooked it up to my truck. Ever since I bought the D, the running lights for the trailer haven't worked, but all the lights on the D work.
The wire colors are Black/White (ground), Blue/White (Battery voltage via "Smart Junction Box" in right kick panel), and Green (input circuit to Instrument Cluster).
By law, trailer lighting must be connected into the tow vehicle's wiring system to provide trailer running lights, turn signals and brake lights.
The wires in the new Tesla (since new sensors, late September) are a different color than those posted above. Everything is working fine except the running lights which wont come on at all. The trailer cable fits easily under the hatch door and stores Wiring was very time consuming.