I know that my truck is under warranty but before I take it in just wanted some opinions. My truck has just 1900 miles on it and when first started after sitting awhile the alternator will not charge and when it does start charging, it will charge for about 10 seconds and then shut off and then charge again. not only does the gauge fluctuate but you can watch the headlight dim and then get bright again. Once the truck is warmed up this issue goes away. My guess is that its in the regulator of the alternator. Any thoughts, Bad alternator maybe it needs to brake in (which I doubt).

 

This is normal, what you are seeing is the manifold heater in operation. I asked the same question to my service dept. about the same thing, with about the same miles on my truck.

 

Like KCCTD said, this is your intake heaters cycling on and off. Totally normal in cold weather.

Is this your first diesel by chance? Do you plug her in during the cold weather?

Your truck has no glow plugs, so the intake air is super heated to aid in combustion. The heaters draw quite a bit of current. You are seeing that draw when the volt gauge drops and your lights go dim. She's just doing what she was designed to do.

When the heaters turn off, your voltage jumps back up to normal on the gauge. That indicates your alternator is working properly


Good luck with your ride.