Hi again everyone. I actually had found a couple of very helpful YouTube videos that showed step by step routing the cable from the detector down the passenger side A pillar and below the glove compartment finally terminating at either the car lighter or the USB power. Those are the safest places to tap. Unfortunately the shop I used refused to look at the video insisting that there 20 years experience trumps a YouTube video. Yes, I should have left right then. But the guy said he worked on Bugatti’s, Lambos etc. in hindsight, I should have known better. The Tesla is is an EV and the electronics are sensitive. Tap into the wrong wire and you will have the same thing happen to you as did me. Anyway, I took the car back to the guy and told him what happened when I plugged the R3 in. The errors that suddenly appeared. I insisted that he remove the wire where he tapped and repair and shield the existing line. Then I showed him exactly where to tap into power. (The right side of the center console near the bottom. I also showed him exactly where the car lighter port was since he told me the car didn’t have one the first time he installed. He opted to tap into the line leading to the car lighter. It now works perfect. Comes on only when I enter the car and turns off after exiting. What a hassle though and who knows if there will be any irreparable damage from his earlier work. It was an expensive lesson plus I still had to pay the original $160. I share this with all of you so you don’t make the same mistake. If the installer has never worked on a Tesla, I recommend walking but if you are too lazy to find someone else, at least force them to watch a YouTube video on the matter.
As an aside, I have only heard bad things about tapping into power at the mirror. Don’t do it.
