How To Install Trailer Wiring Harness on 2014 BMW X1

Updated 06/25/2020 | Published 06/23/2020

Question:

Hello, I bought Curt Upgraded Circuit Protected Powered Tail Light Converter w Hardwire Kit and Tester - 4-Pole Flat. I installed it and as far as I can tell all the wires are correctly connected. Everything works, BUT the brown taillight wire is always on, even when the car is off. The brown wire before the circuit protect unit is acting correctly. That is when the tail lights are on it is at live, when they are off and the car is off it is at 0 volts. Could the circuit protect unit itself be bad?

asked by: Ben

Expert Reply:

The 2014 BMW X1 uses a multiplexed wiring system which means either the vehicle’s brake and tail functions are combined on one wire and the turn functions are on separate wires or the vehicle’s brake, tail and turn functions are combined on one wire. In order to determine which you have you will need to test for this with a circuit tester.

Therefore, when installing a trailer wring harness like the Curt Upgraded Circuit Protected Powered Tail Light Converter part # C59496 you'd not connect the brown wire.

expert reply by: Conner L