Alternator cycling

[Scott6]

Hey guys, this might just be how cold it’s been lately, but I noticed my alternator seems to be cycling on and off frequently when idle. I can’t say that’s I have even noticed it before, hence why I’m asking about it. I also notice a little rpm jerk when it does

normal? I need to pay more attention but I think it is doing it more when it’s really cold, which would make sense since the battery voltage will be lower there

video:

 

[AH64ID]

Does it do it for more than 2 minutes after starting? Or after you've hit 18 mph in the first 2 minutes?

If not then it's perfectly normal as it's the grid-heater doing the post-heat cycle.

 

[Scott6]

Oh crap I totally forgot about the grid heater is kicking on when it’s cold, I was just thinking alternator . it’s not doing it doing it right now at all driving home. We just moved here I’m Not used to being in Weather below 50, let alone 26* in the am. Truck does all kinds of new things haha.

 

[Ozymandias]

You'll also find out about the 3 Cylinder cycle if it is cold enough.
Also the automatic idle up at great cold.

The car has some tricks that not everyone knows about.

 

[AH64ID]

You'll also find out about the 3 Cylinder cycle if it is cold enough.
Also the automatic idle up at great cold.

The car has some tricks that not everyone knows about.

Won’t get 3 cyl on anything but a VP truck.

It will go directly to 1,000 rpms right away when it’s cold enough. IIRC it happens around 15-20° IAT.

 

[Ozymandias]

Mine did it more then once in the great cold, means -20F.

 

[AH64ID]

Mine did it more then once in the great cold, means -20F.

That would be the first I’ve ever heard of any 3rd gen doing it. I’ve been -25°F on a cold start and never seen it.

There isn’t even a programming option to enable/disable it like the VP trucks.

Im guessing it was just the extreme cold and not 3 cyl.

 

[Ozymandias]

That would be the first I’ve ever heard of any 3rd gen doing it. I’ve been -25°F on a cold start and never seen it.

There isn’t even a programming option to enable/disable it like the VP trucks.

Im guessing it was just the extreme cold and not 3 cyl.

I don't know, it was always when idling for a longer time without EB on and without High Idle active.
Maybe after 5 min. of runtime.
Pretty predictable then.