Recommendations for Running 12V Power Wire on 2012 Ford Focus Trailer Wiring Harness 118549

Question:

Instead of running the power wire all the way to the front of the car can I simply tap into the rear fuse box located in the trunk and if so what would be the best way to do this.

asked by: Scott

Expert Reply:

In order to protect your vehicle wiring, it is really best to run the 12V power wire up to the positive battery terminal in the engine compartment of your 2012 Ford Focus. This ensures that you have a direct connection to a 12V source, and that there nothing else pulling power off the same wire.

When you tap in at the rear of the vehicle, you run the risk that other functions or accessories have been connected to the same 12V line, which could cause an overload or back feed of power through the wiring harness if there was a short or bad ground at some point.

Running the wire to the battery is safer for the harness and for the vehicle wiring, and it is not especially hard to do. You should just be able to follow the existing vehicle wiring under the vehicle, along the frame, and up into the engine compartment. If you run the power wire with the factory wiring, you get the most direct route that avoids areas that get hot or that might pinch the wiring. I am including a link to the installation instructions for the # 118459 harness for you to reference.

expert reply by: Sarah L