If you're going to be adding some aftermarket accessories to a G500 Mercedes Benz, chances are you will probably need to find switched power. I recently added an aftermarket In-dash/Navigation stereo in one of these vehicle. I tapped into switched power at the fuse panel on the driver side of the dash under a plastic cover.
I used the empty (A) fuse terminal, designed for the rear heated seats.
I made my own fuse tap, with an inline fuse.
I connected it to the top terminal, that should be the side that meters switched power. I recommend wiring a relay if you need more than about 1-2 amps.
(86-Switched Power From Fuse Panel / 85-Ground / 30-Battery / 87-High Current Switched Output)
-Jeremy's Car Audio Tips
