We have a 2004 F250 super duty diesel truck. My son and husband where hooking up rock lights and to reach my husband had to remove 1 battery. When he did that the line numbed the frame and arched. Now putting batter back in it won’t start. Any ideas? He took the starter to get checked it was fine and batteries are putting out 12 like they should be. At first try rock lights where lit but no crank then lost power everywhere.
Check the starter relay.
I did it was fine
Have the battery that was shorted out load tested. Voltage readings without load don't mean much. It sounds like there's an internal battery failure that breaks down under load.
I have a load tester here hut I will take it somewhere and have it tested
That would be the place to start. Most stores that sell batteries like Autozone will do it as a free service.
Try checking all of your fuses and check for any loose connections or frayed/broken wires. (Maybe a short or bad ground, Etc.) Have your ECM checked on case if it got fried?
Ok we have checked all fuses and wires but I will tell him about ECM
I have 12.2 volts to the fuse box. When I turn ignition on it drops to 4.3.
I have checked batteries, I can jump starter, I still have no power and no headlights.
Can you jump the truck from another vehicle?
If so ur battery may be trashed or a blown main fuse link
Not sure where they are located
batteries tested good. The truck will crank when i jump the starter solenoid but will not fire because i have no power. I have 12.9 volts going to fuse panel until I turn the key then the incoming hot wire drops to 4.9?
did you check both batteries independently?
ie: isolated from one another