I wish I was well versed in electrical systems. I would start with checking all your fuses, may as well. The car should have a few spares anyway. I'm more of a block of steel person.

If you don't know how to check you're fuses, look up in the MB manual and locate where they are. Then pull them out and see if the metal part inside is at all broken. If it is, replace it.

I did have something similar happen to me awhile back though driving 1k miles to florida in a buddies (old) car, it was the Distributor Rotor or Distributor Cap. I don't recall.

All we heard was humming aswell.

Good Luck

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2002 Mitsubishi Galant ES: Daily driver
1987 300E: Still runs, but thinking about doing an overhaul.

Former name, Chris17H. Can't remember my password for anything (4-6 years since I have been back on this great site).