How to Find Stop Light Switch During Brake Controller Installation on 2017 Subaru Outback

Question:

I for the life of me cannot figure out how to detect which wire is the Brake Lightinch wire in my dash. How do you detect which wire has current with just this probe circuit tester? There is not exposed wire, and the adapter head is way to small to get the probe to touch any part of the wire. I have everything else installed, but am at a stand still until there is a simpler solution to this brake wire issue for the Trailer Brake Control installation.

asked by: Blye D

Expert Reply:

When installing the # ETBC7 on your 2017 Subaru Outback, you can test to see which wire is the stop light switch by pressing down the brake and seeing which circuit is receiving power and testing with a circuit tester like the # PTW2993.

I've attached a video of the installation of a Tekonsha Prodigy # 90885 that details this process that you're trying, but if you fastforward to around the 14 minute mark, you'll find exactly what you're looking for.

expert reply by: Erik B