2006 Chevy 3500 with a duramax battery drain

[ALLTERRAIN]

How about lighted vanity mirrors in the visors? Have seen soo many that have flip up covers that stay flipped up and visor folded back up!! Also check to see if the alternator is good, bad regulator can keep it powered up draining the battery with engine off.

[deerlick]

we see quite a few of those with the heater control head causing your problem