[Steeveedee]

If you have NO aftermarket devices installed in your truck, the only thing that I can imagine draining the battery is a bad alternator diode (or a stuck horn relay, stuck tail/dome light switch, etc.). That said, an aftermarket radio or an electronic trailer brake make a draw, but my battery doesn't go dead even if I don't drive my truck for a month or more. Something as simple as dirt on top of the battery will drain it when the humidity is high. When I worked as a mechanic and people came in with a low/dead battery, and the top was filthy, I'd put a voltmeter on it and show that there was potential all across the top of the battery. Of course, I would check the battery condition and charging system, and if they were OK, I'd tell them that the problem was just the wet dust on the top of the battery. Cleaned it off and sent them on their way.