i just bought an 89 ram with a cummins. the battery wont charge. ive already replaced the alternator and belt and also tried to use a different battery. the battery wont charge while the truck is running. any one know what else i can try??

 

voltage regulator is bad or there is an open circuit somwhere. [best guess]

 

i replaced the voltage regulator how would i know if it is an open circuit

 

how much voltage are you getting at the battery with the truck running? how much voltage are you getting at the big lug on the alternator with the truck running. if you are getting 14 at the alternator and 12 at the battery you most likely have a blown fusible link.