Replaced the alternator on my 2004 f250 diesel 12 months ago, the truck ran great until just recently when started it demonstrating same problems as before, batteries would not hold charge and lights on the dash would flicker on and then totally off. Replaced the alternator again and both batteries, was running great for 4 days and now is doing the same thing, would not start, the control panel would flash on as though it was going to start and then turned off as not enough power to start. I was thinking maybe it could be the voltage regulator but understand that is built into the new alternator, so should be ok, unless of course it is faulty, any suggestions? Thanks

 

Have you had the wiring checked?If your alternator and batteries are good,and operating correctly there's not much else,especially if it's a recurring problem....