I have always tapped through the electronics around the mirror. At least 7 cars. All worked beautifully and switched with ignition. #8 was my w205 C63s. I had a successful tap but it is always on and drains the aux battery. I couldn’t find an easy switchable line there. I am a little hesitant but I do need to try to redo the C and also do the GTR. If I find anything useful I’ll for sure post but that could be months...

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I use blendmounts on all my cars, but since there is not one available for the GTC I decided to cut the suction cup off the factory mount on the Escort and use black silicon directly to the windshield. I tried the suction cup a couple years ago and it fell off in the high heat so I wasn’t even going to risk it on the GTC. It’s pretty easy, split the housing on the windshield behind the mirror. It separates left to right, you don’t even need to remove the right side. Behind the left side there is a plug with 3 wires. Tap into the brown and red wire. I ran my wire through the cover vent before I did this. Snap it back on and your good to go. The radar comes on at start up or when you enter the car and will go off on the final hibernation mode, not the “door open and exit mode”. This is around a minute or so, never timed it, but works great on my car. Hope this helps some, I never could find shizzle on it.