Homelink mirror

I know this has been posted about before but I recently got a Homelink mirror for my 2020 SR. I have the wires ran to the driver footwell but cannot for the life of me find a switched 12 v to tap the wires into. I want the garage buttons only to work with switched power like the rest of the mirror

 

Not the answer you seek, but isn't that opposite of the factory operation? I am able to open/close the garage doors at anytime, no need to start the truck or anything.

Could you just use a test light on the fuse panel and find something that cuts power when off, like the wipers?

 

What model do you have, some of these have batteries that are good up to 10 years for the garage door opener function so no need to even run wires.

 

Its better to have the garage buttons only work when trucks on. This is why I dont use mine. If someone breaks into your truck its like a key to your house having the button work all the time.

Reminds me to look into getting mine rewired so it's off when the truck is.