I have a 97 Dodge Ram 3500 with a 5.9. My problem is the voltmeter charges and discharges almost constantly while traveling down the road. Thought maybe it was the alternator, but that wasn't the problem. I think it may be the air intake heater. Any thoughts would be greatly welcomed.

Sounds like grid heaters cycling.They should kick off when you reach 20 mph or so.If not there is something wrong.Not sure where they get there signal from,maybe someone else will chime in.Mine will cycle til I hit about 24 mph...Doug

There is a sensor in the intake that senses the air charge tempature and tells it when to cycle.