I finally have all the parts to install an empeg in my 2002 Mercedes-Benz E320 wagon. Many Benz from this year used the same headunit, so I thought these empeg in SLK and Pioneer in SLK instructions would work. Unfortunately, their wiring harnesses don't seem to match mine.

Is it possible to determine the function of each power/control wire? Or will the 12V line melt a voltmeter? I have no idea how to read a voltmeter or how to set it up to work. Any tips?

Are these assumptions right: 12V gives a big signal when the key turns on. Ignition sense powers weakly at that time also. Toggle seadlights to find headlight sense wire. Ground must be the thick black one. The final one must be amp sense. But... what if they have a wire that the empeg doesn't...

The wires in question are:
Grey
thick Red with White stripe
thick Brown - ground?
Yellow with Black stripe
Blue with White stripe - amp sense?

Or does anyone know where to find this wiring diagram? I've been looking for a while now with not much luck. Thanks all.