How to Wire a Truck with Separate Stop/Turn Signals to Work with Trailer with Combined Signals

Question:

So we are wiring a truck with the turn signals and blinkers on oposite wires. We are running a dual red light option on truck where one light will be a brake light and one light will be a turn signal. How can we wire that up but still pigtail off it for a 7 pole trailer light plug. Iv done it before but i cannot remember how i did it. Help please

asked by: Matthew

Expert Reply:

There are few ways to go about this, depending on what you've already installed on your vehicle.

Without knowing the year, make and model of your truck, I can recommend universal parts to get the job done. You'll need to start out with a 4-pole hardwire kit that is designed to convert your 3-wire system (separate stop/turn signals) to work with the 2-wire system (combined stop/turn signals) on the trailer, like the # C59496.

From there, if all you're wanting is to control the basic trailer lights, you can plug that 4-pole flat into an adapter like # 37185, and tape the remaining wires out of the way. That being said, most trailers with a 7-way are equipped with electric brakes. Our # ETBC7 kit is what I recommend if you're looking to install a fully functioning 7-way on your truck. It includes everything you need to complete the remaining connections, as shown in the attached photo. I've also included a couple helpful articles as well as an installation video for you to check out at the bottom of the page.

If you can tell me the year, make and model of your truck as well as what wiring is already in place, I can probably make a recommendation for a vehicle specific 4-pole flat harness that won't involve splicing each wire, to save you time.