92 Voyager 1/4 a current leak?

I'm working on my friends 92 plymouth  Voyager, and she complains that the battery keeps going dead. I put an ammeter at the battery, and found that a .25 amp current is present when the car is shut off, empty, and all lights are off, and doors are closed.

 I trouble shoot, and found the pulling fuse f3, the interior light fuse, causes the current to drop to zero, so I know the problem is somewhere in the cab.

  With the fuse in , and the I leak back, I pull both dome lights...still no change. Does anyone have a decent schematic on this electrical system?  The Haynes Manual I bought doesn't show F3 as being the doom light.

  BTW, when I first put the I meter in line the current starts out at about 1 amp or so, and drops off to a min of .24 a or so after just a few seconds (a incandesent bulb getting warm?)

Thanks

 R Foy

There is a speaker in the engine compartment, that could be for an alarm, (but I disconnected all the leads to it) and there is a misterious small black box above the drivers legs under-the-dashboard.  (havn't tried disconnecting the leads to it) The black box is a funny looking thing, smaller than a matchbox, with no markings or apprant use.

 Does anyone know the 'common' amp/hr rating of a car battery? If it's 200 amp/hrs or so, a 1/4 amp should not really hurt it much. Could this leak be normal?