sounds like honda ELD, if you watch you charge voltage does it ever drop randomly while not beating on it? didnt think american trucks had it but idfk, eld basically turns off the alt while driving and kicks it back on once voltage gets low enough, only problem is that it senses your cars demand and not the overall for amperage so for example in my wifes car i make her run ac 100% of the time because the system senses the ac load and will kick full tilt aka alt stays on.
Also what are you even charging at?