Troubleshooting 2016 Mazda CX-5 Wiring Harness and Trailer Lights That Hyperflash

Question:

I installed the kit for a 2016 maxda cx 5. It seemed to work fine when we tried all the signals and brakes etc. Then when I hooked the trailer again to drive with it the brake lights worked but when we tried to use the signals the suv signal noise blinked hyper fast but no suv lights blinked and no trailer lights blinked.

asked by: Paul Z

Expert Reply:

Since LED-type trailer lights use so little power as compared to the standard incandescent type bulbs - about one-tenth as much - there can be weird interactions when a trailer with LED lighting is connected to a vehicle wiring harness intended for standard bulbs. It sounds like perhaps the wiring harness you installed is not the correct one for your CX-5.

If your car has LED taillights then the correct wiring harness for it is Tow Ready # 118563. If the car does NOT have LED taillights then instead you'll use Curt harness # C56011.

Because cars with LED lights use lighter-gauge wiring (since less power is needed) the wiring harnesses for such cars will be the powered type that use a separate power wire that runs up to the battery to deliver the actual power to operate the lights. Harness # 118563 has such a design and its intended purpose is to protect the car's delicate wiring from the risk of overload from a trailer that pulls a lot of current for its lights.

Hyperflashing in LED trailer lights can be corrected by installing a load resistor inline with the power wire. Part # DI34ZR is a ceramic load resistor that lets an LED light appear to be a standard incandescent light to the wiring harness and will prevent hyperflashing.