looks like a bad grounding situation here or the can going crazy.

The 2 main grounding bolts in the W210 cabin are located one near the battery behind a plastic cover (its also used as a battery disconnect sometimes) - and one is a clustered ground near the center console on the passenger side.

Remove the carpeting to find it and clean it out very good - its a layered ground so take out each eyelet and clean it.

The other point can be a faulty can service connector, it looks like a harmonica with mini plugs in it, clean that out and recheck it. I have seen one car with a wet connector doing all sorts of idiotic acts like this.

Other than that - you might want to look for pinched wiring

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)