Check gauge shows up volt meter goes dead
truck runs for a lil after then lights on dash show up and truck dies

use a jump box fires back up does it again

I got a new alternator does it again , wires look still good bother battery’s are charging when I fire truck up but does it again

any clue to what can be doing this and I let it test for awhile I jumped it back on , volt meter is between 8 n 14 v but it’ll die once I drive it again

so once that check gauge shows up I know my battery’s ain’t being charged anymore and they get drained

 

These trucks have the alternator hooked to one battery, and the power distribution center and ECM are hooked to the other.

If the parallel cables are sketchy (they might look fine and ohm out ok, but have high resistance when carrying significant current) it can cause the ECM to command the alternator to full output, leaving one battery not fully charged and the other over voltage.

it might be worth taking a minute to put an electrical load on the truck and take a voltage meter reading from the negative post (not the clamp or cable) to the other battery negative post, and do the same thing positive to positive.

small fraction of a volt across the cable would be fine, but if it’s bigger than that….