The truck is making a clicking noise in the dash with the key off and the battery switch turned off. It kills the batteries by morning. If I leave the battery switch on no clicking and batteries are fine in the morning.....
I had an idle timer on my 2000, used to do that. I unplugged the timer, taped wires off. Longshot, but maybe there an old timer in the dash? All I can think of.
Its back feeding somewhere if i turn off the batteries the check engine light comes on and the flasher relay clicks. And the grounds become positive like the steps,fuel tanks and cab of truck. The battery shutoff is on the ground side of the batteries....