Ok. So you put a scanner on the truck and it said low voltage, what was the code if any.? If you have a code, then Google is your friend. You can Google the code for dodge ram and it will usually list all the potential things to check to help resolve the problem.
If you have done this and it's still unresolved. Will the truck start or run?, if no then you have to look further at specific components in the electronic pathway.
Your model year is bad to have issues with the tipm. Have you checked this? Have you seated and unseated this unit? Have you looked for evidence of corrosion in this unit? Looking at your location by your zip code, rust and moisture could have taken a hold to some of the electronics.
Don't just fire the parts cannon, think, the battery is new, the alternator is new, those components should be good what's next. Has the truck been wet under the hood?
If you can't do further diagnostic work yourself, where is the closest dealer?