When I start, the lights get dim for a couple of seconds then get bright. They do this several times. Initially, I thought that it was the intake heater grill kicking on and off, but they do this even when the engine is fully warmed up.

What gives?

 

Mine does the same to the point of actually seeing the lights slightly dim. I would guess that it is the grid heater's cycling on and off. If in doubt I would take it in to the dealer to have it checked. It should still be under warranty?

 

Some other load cycling on and off , like AC-defrost uses AC to help .

 

probably the intake grid heaters, if it's cold outside, I beleive they are triggered by outside ambient temp, not engine temp

 

It's normal guys. It's the grid heaters. They go on and off below 30 MPH when the air temp is below 50F. (I think) Engine temp has nothing to do with it. There is a way to run the power source through an poil pressure switch to shut it off when the engine is running if it bothers you. To me it is added wear and tear on the alternator, and grid heater relay that is not needed.

 

Do you know how to do this? Can you post?

Thanks!

 

https://www.dieseltruckresource.com/...ressure+switch

https://www.dieseltruckresource.com/...ressure+switch