W210 E320 1998 random elecrical failures
 

Good morning! My '98 E320 has been experiencing some odd electrical issues for over two years. I've searched and searched and haven't found a fix. It's having random elecrical failures. One day I start it and the driver's seat, exterior mirrors, and passenger side window will not work. I disconnect the battery and reconnect, all works again for a day or so, then the next time no windows will work, the passenger seat and mirrors won't work. Reset by disconnecting the battery and all works for a day or so again, then the driver's window and maybe a rear rear window won't work. Sometimes, I'll reset it and all works for a week before a failure. Also, if I let the car sit with battery connected for a week without driving it, the battery will go dead. It's a 1 year old battery, but the same was happening with the old battery. One Mercedes mechanic said it could be the old original keys causing it? Seems to me the ECU may be failing somehow, because it's so random as to what will and won't work on any given day. Have of you W210 owners experienced these issues and what was the fix? Thank you! I've watched this site for years but rarely have I posted for help. The car has been very well cared for and only has 113,000 miles on it.

Mice? I had to put poison bait under the hood

body control module maybe

For wider exposure for your issues, Benzworld has an active W210 group. MBWorld also a possibility.

I have the same car - 1998 E320. Low battery voltage at user or poor connections could cause those sort of problems. Could also be you have a short or drain somewhere.

When I had similar but not as severe problems, I changed the battery even although it was fairly new. Solved problem and I later used the old battery in another car that was not so sensitive to battery voltage! Maybe get battery and alternator tested at a shop or if maybe a parts store. Current leak can be in alternator.

I also recall measuring battery drain current while removing fuses. That may pinpoint your problem if it is not the battery that is defective.