It seems on my E420 W124 1995 I had this problem caused many electrical things to short out Alarm, front seat control module, and door lock pump, also a resulting direct ground caused a fire under floor plate front passenger side, I tried drains on cowl, sunroof, windshield rubber seal, blower motor seal, etc it ended up being these rear plugs in the wheel well. Now I have a lot more repairs to be done.