Depends on the year. If it's a 2018, there's an empty slot you can put a terminal into near the driver side kick panel. If it's newer than you can always tap the 12v cigarette lighter or you can just wire into the 12v penthouse underneath the rear seat. I have a 2018 so I was able to put the terminal into the open slot behind the kick panel. Some have said you can tap the wire that's in the spot even if it's populated. Radar detector stays powered on for 30min or so after I exit the vehicle until it goes to sleep or if sentry mode is on. There are a ton of threads on here about hardwiring a radar detector.
Folks! I'm trying to figure out the best method to connect my radar detector (Uniden R3) to my M3. Has anyone did it to a 2020 model yet? Or even a late 2019? From what i can tell, there are 3 options: 1. Rear View Mirror tap - connection is too tight to use AND power source is constant (not...
teslamotorsclub.com
Here are the instructions I followed.
How to Hard Wire Install a Radar Detector to the Tesla Model 3