I actually had the same thing happen to my 560 SEL. I had a short related to the anti-theft system. Anyhoo...I kept blowing the fuse that is responsible for among other things, the memory seat function. If you open your front drivers side door, the rear courtesy lamp (top rear middle of headliner) should come on. If it does not come on, then look at your fuses. I can't remember the fuse number ...i think it was #15 that kept blowing. Hope that helps.

__________________
1990 560 SEL- "Goldielocks"
1984 300SD TurboDiesel- "Ole' Blue"