2013 Sierra Texas Edition

[BarryKH]

Is there any way to tell if my truck . has already been tuned. I've been driving it in ways to see if it goes to v4, but so far I haven't seen anything but v8. Maybe I'm doing it wrong, but I was wondering if the previous owner had it tuned. Thanks in advance.

[diyer2]

Get on a flat stretch of highway. Trans in drive. Keep a constant speed. When there is no load on the motor it will go into V4 mode.

[BarryKH]

Ok, thanks I'll try that.

[BarryKH]

I drove the truck several miles at no load, no air, no anything, some of it on a gentle downhill grade and it never went to v4. I'm beginning to think it may be tuned. It really runs good and the 6 speed tranny really shifts great. Sounds great too.