Join Date: Jul 2007
Location: Truckee, CA
Thanked 116 Times in 114 Posts
Rep Power: 8
Re: Trailer light genius needed
Suggest you measure voltage at each contact on the vehicle plug. Start with the "tail", lights on, find 12 volts and record the color. Then turn on the the right turn light and find the contact, record color, same for left turn.
Open up the trailer wires and match accordingly to the plug. "Tail lights first until only the trailer "Tail" lights are on. Then, right & left turn lights. On some vehicles that use separate turn and brake light filaments, you may have to get an adapter to combine them into your trailer 3 wire plus ground plug.