Mystery Wire?

[chrisbmo2000]

I pulled the factory trailer wire harness down on the truck today and what do I find .........It had not been used....at all so I start hooking up the wires and I have an extra....it is light green and of a smaller guage than the rest.....is this an acc wire for the trailer(ie interior lights ect) or did I miss something? If this is an acc wire what powers it?

[redvett]

LT Green is the backup lights, just use a test light and check the circuits.

[handsomerob]

He's right it is for the backup lights. Not needed for a standard 4 wire trailer harness.