I know the 09+ have the descent assist.
THe 08 may be similar.
If youre in D, and going downhill, and youre applying the brakes- the computer- will help you- by downshifting.
Youll notice the RPMs go up.
If you dont want this- Shift to L, and 6.
Or before you hit the hills, shift to L6, and the feature is deactivated. Youll notice the vehicle roll down the hill without the computer helping you
2010 FWD LT1-Gold Mist Metallic- seats 8
Build Date- July 31, 2009-2nd day of Spring Hill 2010 production.
2013 Equinox 3.6L 83,000
2010 Traverse 3.6L 148,000
2003 Trailblazer 4.2L 181,500