my 1997 Dodge Cummings is acting up. all at once I lost the tachomitor the a/c stoped the altonator quit and the check engine light came on. I was told it was the engine speed sensor so I replaced it. the same conditions exist. I bench tested the altenator and its good but its not charging the system any one know what might be going on here? Did the ECM die?

 

120 amp alt fuse?

 

Sounds like your ecm