Rolling while parked

[profiler7]

I have a 2018 GMC Sierra crew 4x4 SLE. IIRC, the day I got it (March 2018ish), I parked in my driveway and went inside...then noticed it rolled down my driveway — while in park, no parking break. Played with it a bit but couldn’t replicate it. So I started using my parking brake. 

 

Today I get home, 1/8” of snow/ice on the driveway, had to put in 4 wheel to back up the driveway because of the awesome Goodyear’s, park, switch back to 2 wheel, apply parking brake. Half hour later the neighbor stops by because my truck was in the road. 

 

It did not slide, it rolled while in park and with the parking brake applied. This is my 3rd Sierra, first time experiencing this. 

 

I actually watched this happen probably 2 years ago with another neighbor. I was walking down the street with my daughter and thought they were backing out but their Cherokee just rolled down the driveway on its own from a parked position. No snow; just rolled. 

 

What the hell is going on?!

[grizz_wi]

I'm glad it wasn't just me, thought I was nuts, I went to hook my trailer the other day and it rolled a good 2 feet down my driveway then stopped. Couldn't replicate it as well..

[greatmizzou]

Would this be a transmission issue? Clearly your brakes and parking brakes function fine.

 

 

maybe try putting it in park and pushing on it ( in a safe place) when on level ground to see if there is ever a time you can easily push it back several feet

[profiler7]

Hopefully not....

 

I wonder if it had something to do with the 2 --> 4x4 shift then back to 2 shift while parked.