Problem with a 2015 Chev 2500... (RT 170)

[mumkin]

I was finishing up before I head south - leaving tomorrow, but needed to air the tires and pick up a couple last things. At Tires Plus when I turned off the key, it seemed to keep running and sort of shuddered to a stop, but I had the radio so loud, I wasn't sure what it had done. At my next stop, I turned off the radio and sure enough... all the lights on the dash turned off properly, but the engine kept running smoothly with no change for maybe 5-7 seconds and it finally stopped. (it was properly in park) I finished my shopping and the first turn of the key, it didn't want to start, but second time, it started right up. It did exactly the same at my next two stops. I've had lots of cars for lots of year and this is a new one. Doesn't seem to be the starter... perhaps the ignition switch on the column is going bad? I have an appointment with Chevy for tomorrow morning, but I like to have some idea of what it is before I turn it over a garage. (guess I won't be on the way for another day... or...)

It wasn't like the old fashioned "dieseling" problem... (plus it only has 15K miles mostly highway driving)

Someone on Facebook suggested it might be the "Fuel cut-off/solenoid"

Any thoughts RV gurus?

[booster]

That time frame is likely about what it would take for the fuel pressure to drop, once the fuel pump is shut off. Normally, they would stop the engine by shutting off the ignition, so it would be more likely something is keeping the ignition active once the key is shut off. Lots of things could cause that issue, I think. The good is that it does it all the time, so it should be easy for them to find at the dealer.

I do hope that whatever is doing it eventually goes off, as you could wind up with a dead battery if it doesn't.

[mumkin]

The radio goes off when I open the driver door as always... which seems a good sign. Not sure what else would stay on and be parasitic... though if it doesn't start tomorrow morning...

I'm hoping that they will plug in their little computer and it will tell them what it is....

[mumkin]

Chevy called and it was a bad computer module. They are replacing under warranty.

If I can get more specific information when I pick it up, I will add it.