Hello. The other day I had a Tekonsha P3 Brake Controller installed in my Subaru Outback. Since I don't yet have my lights hooked up on the trailer, I wanted to
test the 7 pin connector that was installed with the brake controller. To do this testing I bought a Curt socket tester (see attached photo). All the LEDs on the tester
illuminate when they're supposed to with the exception of the BU labeled LED, which is the tester for the "back up light or auxiliary power". The instructions for the tester
say this LED should illuminate when the tow vehicle is put into reverse. It does not illuminate so asking if anyone has any insight into that and why it might not be illuminating...
and whether there might be an issue with the installation wiring. I have no experience with this sort of thing.
Thank you for the help.
John