Why Does Trailer Wiring Harness for 2017 Mazda CX-5 Require Running Wire to Battery

Question:

I have watched 2 installation videos for installation of curt wiring harnesses. 1 requires you to hook up to the battery and the other does not. Why is it necessary to fish a wire through the trunk and run on the underside of the car to then fish into the engine compartments to tie in to the positive terminal, if the trailer light will work without the positive wire being connected?

asked by: Adrian

Expert Reply:

Not all vehicles can handle the additional amperage draw of the trailer taillights on the vehicle taillight circuits. Those vehicles need setup that draws power from the battery. Some vehicles have higher rated circuits that can handle this, and others need to have the power drawn straight from the battery to protect the taillight circuits.

For your 2017 Mazda CX-5 you need to install a harness that draws power from the battery to protect the taillight circuits. For that you would need the part # C56377. I also attached a help article on running the power wire for you to check out as well.

expert reply by: Jameson C