Oldsmobile/Buick Repair: battery goes dead overnight, buick lesabre, altenator

Question
90 buick lesabre 3.8 v6      runs fine.battery charging normal.park all night and battery is dead in morning.tried several new fully charged batteries.pulled all fuses disconnected altenator and anything electrical we could find .draws about .4 amp with everything unhooked.

salv0@comcast.net   thank you SAL

Answer
hi sal,ok sounds like you have done all the proper testing, but what i believe is going on here is a relay is stuck.either the fan relay cooling fan relay or possibly air susp relay.start unplugging relays until you get the draw down to 1 amp or so .good luck billymac