I have the same problem, which I think is caused by the insulation on the dome light wires wearing out, exposing the metal wire where it is clipped to the sheetmetal under the driver's side rear pillar/headliner, & the wire shorting. The dome & trunk have a common ground according to the wiring diagram I read.

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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)