2017 with 6.2 occasional slow to crank

[Mattbmx63 0]

I have a 2017 Sierra with the 6.2. Sometimes when I go to start it, it will crank for a second, start cranking very slow then back to normal. Other times it may barely crank for a second then start. Have load tested battery, no issue found. I just drove for 30 minutes, stopped to get gas, when I went to start the truck, very slow cranking for a couple seconds then normal cranking and it starts. Dealer claims no issue.... any idea's?

[Snowcamo 518]

My money is on the starter,  grounds or battery cables. 

[JimCost2014 1,479]

If it is the original battery, that would be my guess no matter what the reading was.

Edited Tuesday at 12:34 AM by JimCost2014

[draperfish 37]

My 2018 was doing the same thing, it was the battery, had a bad cell. 

[goeb34 39]

Try uploading a video next time? I feel like my truck does what youre explaining but not really sure.

[midwestdenaliguy 132]

Assuming it's the factory battery, it would be ~4 years old at this point. You *might* get another year out of it so I would just replace it at this point. I've had batteries over the years do weird stuff that didn't quite make sense to me but once I replaced it the problem went away. If you find out it's not your battery after replacing it then you're not really out anything since it would be smart to replace it this year anyway. Start there then continue to diagnose if it still persists.