Chevrolet Repair: electricial problem 2000 chev pu, fuse panel, circuts

Question
All of a sudden the battery started going dead overnight.  I did a peliminary check of the fuse circuts and found i have a draw on two of them.  One is the radio and is the lesser of the two and it's probably a normal parisidic draw. The other one is a 50a fuse labeled RAP #1 and it has a pretty good draw on it.  I don't have my digital meter with me so i can't tell how much, but it will light up a 12v bulb.  What does that fuse control? It is located in the main fuse panel under the hood and next to the 50a ignB fuse.  2000 chev 2500, with 6.0L V8

Answer
the RAP fuse powers your door locks, pwr mirrors and your pwr seats. it will have a rather large amount of current due to the options it powers. does your radio have a cd player? if so i have seen the eject button stick and it will kill a battery overnight. hope this is some help to you.