What was the outcome - I think I have the same problem, as my becker head unit reads CD M E even though two cd changers have magazines in them and neither works because the input voltage is not 12 volts (closer to .15 mv).

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)