Nissan Repair: battery draining overnight, nissan sentra, aftermarket radio

Question
I have a 1992 nissan sentra classic.the battery is fully charged at night and by the morning its dead.There are no lights on,or anything like that.Could this be caused by a short? and if so do you know the most common areas wher a short would occur on a nissan.thanks

Answer
Check and see if the fuel pump is running all night.  Go behind the car and listen for the fuel pump.  If it is on the relay contacts are welded together.  All you would need is to replace the relay.  If that is not the problem I would be looking for anything that could be running like an aftermarket radio or amp.  I have seen alternators that have gone bad and discharge when the car is off.  But, that is really a long shot.