trailer turn signal ?

$5 says your brake light doesn’t work either. It’s the green wire coming from the multi pin power through the Wesbar harness.

Turn the parking lights on, now Crossways 90 degrees, Plug the brown wire pin on the truck harness into the green pin on the trailer and see if your brake light works? If not then it probably is in the trailer, if it does then it’s on the truck.

Switch your two trailer lights around. Plug the left in the right, and the right in the left and see if the problem follows.

The best invention for trailer wire problem finding, is to get the truck side version of the plug, and put ring terminals on the ground, running lights, brakes/turn signals, and backup lights. Then you can use a spare battery to run which ever circuit you are testing. You know it works from that far back and you just follow it till it fails.

I’m usually swearing at a bad ground.

You don’t need another harness for the truck as you can be sure the ball is grounded and just turn the existing plug 90 degrees to each other plugging in only one pin.

Flashers work same as brakes of you hit the emergency flashers. Use the brown wire pin on the truck and leave the parking lights on. Just plug them in 90 degrees on ne pin at a time and check the lights for operation.

Ed, you have a test lit fixture built into the system. Go to the front of the trailer, unplug the lights and plug the two plug/receptacle pieces in sideways 90 degrees to each other. Look at the wires into the rubber flat plugs, use the one with a brown wire on the truck and plug it in to the green wire corresponding pin on the trailer. If the parking lights are on the right tail light should glow red for brakes/turn signal. Now do the yellow wire and the left tail light should glow red.

Brown – Tail Lights

Yellow – Left Brake/Turn Signal

Green – Right Brake/ Turn Signal

Blue – Reverse Solenoid/Back Up Light(s)

White – Ground under coupler/ Safety Cable area