Passenger side kick panel is the Can bus bar where all the body modules connect there,s like 9-10 wires connected to a bar. On my 2000 W210 the passenger seat module was bad so just left that wire disconnected its been over 2 years now all is good except that seat doesn't work don't want to spend money for new module at least the driver one works now. There's a way to test each module just do some research "W210 CAN bus problems".. On some other threads I read it was common for RR window motor. Hope this helps

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1995 E320
1998 E320
1999 E320 4Matic
2000 E320 4Matic
2000 ML320
2007 C230 Sport
2003 Cadillac CTS