Chris Manchur

I know exactly what you're talking about, have had the same thing happen on my 2015 6.2L. I'm used to the 2009 Sierra starting up much quicker, so I took a look online and found this service bulletin from a few years ago. https://static.nhtsa.gov/odi/tsbs/2018/MC-10137203-9999.pdf Apparently the fuel pressure needs to build up which is why it cranks longer than normal, and so far I've started mine in -25 C weather both plugged in and not and it didn't seem to matter. The bulleting mentions it could take up to 5 seconds to start in those temps, and if you count it out that's a long time! However I've always had mine start sooner.