Haulmark Trailer 7 Pin Wiring Diagram. Tan - right turn signal Black - ground Light green - left turn signal Red/black - stop lamps. Look at the wiring diagram for your truck and determine the designation given to the ground location for the taillights.
The first step in wiring your trailer cables is to ground the white cable first. Time to break out the test light. Look at the wiring diagram for your truck and determine the designation given to the ground location for the taillights.
This is when you need to adapt -- literally.
Look at the wiring diagram for your truck and determine the designation given to the ground location for the taillights.
Refer to your trailer service manual and plug installation instructions to avoid wiring problems that may damage your trailer, brake controller or vehicle! I hooked up to my trailer for the first time yesterday and no electric brakes. Trailers that use this are usually fairly light weight and don't have.