My wife's new-to-us 2000 C230K has a parasitic drain that has me stumped. After a dead battery, I checked for a drain (ammeter between neg post and frame) with a reading of .27A current. After a couple seconds it would drop to .04A, then .08A, then back to .27A. Pulling 7 different fuses would lower it to .24A, then the cycling again.

Question: What would cause it to cycle like that? (Fuse designations seems to point to the window or door modules)

TIA!!!!!

I dunno about Benzes, but GM uses window and seat motors with internal circuit breakers. If a switch stuck 'ON', the breaker would heat up, open, cool off, and close. The result is very much like you describe...a now-you-see-it, now-you-don't current draw.

Disconnect the battery and let everything cool off for half an hour or so. Then, when you reconnect, you might be able to hear where the problem is.

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1989 300 SEL that mostly works, but needs TLC

Try unplugging the seat computers. I worked on a C240 that had a bad passenger seat computer that would keep all the other control units "awake". If you have a bad control unit connected to the CAN it can keep all the others from going into the "sleep" mode and powering down.