Some thing is killing my batterie - 2005 GMC Canyon

The first thing to do is to make sure the battery is good, have it tested and make sure its good and holds a charge, the next thing to make sure the battery is good is to disconnect the negitive battery terminal and let truck sit the amount of time is would take to drain the battery, this is overnite in most cases but im not sure about yours, next after it sits the amount of time then connect battery and it should start, if it doesnt then the battery is no good, also when the battery is tested have the charging system checked to make sure the alternator is charging the battery, after the battery checks out good and the alternator then the next step is to look all over the truck for any light on, like glove box or a light on the rear view mirrror, i will say that this truck is designed to shut down all power left on in side truck after i think 15min, i think you may find a bad battery is the problem but still check for any light on look closely front and rear for any lights. this is where i would start, the next thing would be a draw meter on the battery while you start to disconnect fuses from the box until the draw meter shows no draw anymore then you would see what system the fuse you pulled runs and then check that systems components, but lets start with the batt, and alternator and for any lights left on. hope this is helpful. good luck...