Tail light wire color
 

I'm supposed to help a friend move tomorrow. A friend of his has a small trailer he has offered to let us use. I have a ball on my step bumper (don't worry, probably nothing heavier than a couch will be on the tiny trailer at a time), but no wiring harness for the trailer lights. I picked up a pretty straight forward universal 4 wire kit to slap on in the morning. I was wondering if anyone knew off hand the wire color for the left and right turn signals and brake lights? I'm sure I could figure it out by following the wires and checking with a multimeter, but we have probably a full day of moving crap tomorrow, and I'd like to just go splice it in in the AM with no fuss.

Thanks!

Generally speaking,

Brown=Tail lights/marker lamps
Green=Left hand turn and brake light
Orange or yellow=Right hand turn and brake light

Your wires may or may not have tracers on them, and/or the colors faded, but this will get you in the game I think.
Easiest way to check is with a test light, while using the lights on the truck.

Are we supposed to see voltage on brown when brakes are depressed?

I'm wiring a 4 harness. I guess brakes get 12v from L/R and the brown is a switched ground.

Almost correct. correct wires for trailer connector.
Green is right turn/stop
Brown is tail/ marker
yellow is left/stop

Yeah. I was reading too far into it. Brown was the only wire left (for me) hooked it up and brake lights worked.

All good!

Thanks, boss.

Brake lights should NOT depend on the brown wire; that's the parking/tail light wire. Sounds like you're grounding one circuit through the other. Are you running a separate ground wire from the trailer to the truck? Depending on ball contact for the ground is always iffy.