Why Does Power Wire for Curt Wiring Harness for 2018 VW Tiguan Require Running to Vehicle Battery

Updated 04/23/2019 | Published 04/22/2019

Question:

Hi, I’m about to install the Curt wiring harness for a 2018 VW Tiguan MQB, 4motion, and I was wondering if there is a way to use a 12v car adapter to send the unit power instead of running the black lead underneath the car or through the cabin to the battery? There’s a 12v outlet conveniently located in the back. I guess the other relevant question is does the Curt wiring harness pass through brake and turn signals without being powered. I feel pretty good about the install complexity in the rear of the car, but was wondering if I had to stop before sending the black lead wire to the battery, would my brake lights still function? Thanks!

asked by: Clint L

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. If you run the power wire for the Curt harness # C56403 you have to a different circuit you will have bypassed the circuit protection and would potentially damage the vehicle in the event of a short.

expert reply by: Jameson C