Have you taken the steering wheel off? I took mine off because I was having a squeaking problem and I found out that there is a part in there that has a paper thin wire that winds up like. It seems to me that maybe that wire snapped because it was forced. It carries the wiring for the horn and the air bag. Here in California it costs about $380. Good luck it’s not hard to replace.

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98 E320 175,600m
99 ML320 175,500m
as of 12/2012