Hey guys I've been searching for hours but Ican't seem to find any others with my problem.

Truck was running fine on the way to work...Truck Sat for 24 hours and even I went to turn the key to allow the grid heater to turn on (key on engine off) I noticed my volt gauge around 8 volts...the check engine and warning lights were. flickering and it sounded like a quick ticking noise under the hood...I turned the key as if to start the truck and nothing....I turned the key off for a bit then back on...started out the same way weak flickering of lights and key buzzer then without touching anything it jumped back to around 14v...the lights were bright again the ticking went away and the key buzzer sounded normal...I turned the key one more click and the truck fired right up...drive home no issues...started the day after no issues...I go to start it this morning same problem but this time instead of jumping back to 14v it completely Killed the batteries and wouldn't start....I haven't had time to check it since I'm on a 24 hour shift but I'm confused any help is appropriated

96 Cummins auto

 

SO lets keep it simple, check your battery connections for ANY! signs of being loose or corroded, or broken. next check your grounds to the frame and starter. It sounds like either a connection issue or battery issue. If it killed your batteries you either have a short to ground or you have a parasetic load on the batteies.

 

My buddy's truck kept killing batteries whilet parked and it turned out to be the glove box light staying on when closed draining them