Do I Need to Run the 12v Power Wire to the Battery When Installing the C59496

Question:

I am looking to install a Tekonsha 119147 light kit to my 2015 GLA 250 and am wondering if I could use my rear 12 V power outlet, via a 20A cigarette adapter to power the deviec? Also, do you have the wiring colors i need to hook this device up to my car for brake, left turn, right turn, running lights? Thanks.

asked by: Edward H

Expert Reply:

I do strongly recommend running a separate power wire from the # C59496 directly to the vehicle battery. A wiring harness must have its own dedicated circuit directly to the battery since the 12 volt accessory circuit was not designed to support the additional load of a trailer wiring harness. We have seen many instances where customers have tapped into a 12 volt accessory circuit, like a 12v power supply at the rear of the vehicle, and the harness failed. We have also seen instances where the accessory circuit on the car failed in addition to the trailer wiring harness. Also, this will typically void warranties both with the wiring harness and on the vehicle.

I do understand that running that wire can seem like a daunting task, but we have put together a great FAQ article that I recommend checking out that has some good tips on how to make it a little bit easier. We don't know the individual wiring colors used by Mercedes-Benz, but you can test the wiring using a circuit tester like the # PTW2993; I've also linked some helpful articles on trailer wiring that should help.

expert reply by: Erik B