For what it's worth...if you are poking around above the overhead console where the 3-wire auto-dimming rearview mirror plugs in....and let's say further you are wondering what, exactly, the green, middle lead corresponding to "Reverse" signal actually does...(I dunno...maybe you "won" an auto-dimmer/Homelink off eBay and you've jury-rigged a failed 12V-to-5V USB power-point phone transformer and temporary splices to your "winnings" to move it from car-to-car like it's a hand-held garage door opener)....but I digress....if you run short of hands shifting into reverse whilst trying to hold the neg lead of your meter on a ground point (dash power point) and the pos. lead on the middle terminal....and manage to bump the black/3rd terminal in the connector whilst still in contact with the middle terminal. You can head on back to the boot fuse box and replace the 15A in slot F3. That is all.

Oh, the green wire gets +12V when you shift to reverse...and I mounted the mirror I won in my son's 07 Tundra - Now I have the real hand-held to move between my XJ and the Exc. There's a guy in Frisco who says he can repair my auto-dimmer - which looks just perfect but hasn't done any noticeable dimming since I've owned the car...despite the li'l green LED being functional. Neither any evidence of leakage or surrounding damage.