On the top of this part there is a two-position dial, marked I believe with a 0 and 1. Does anyone know what each position is for? Which way should it point for normal operation? Thanks.

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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)