Unable to Connect to OnStar Message
If there is limited cellular coverage or the cellular network has reached maximum capacity, this message may come on. Push 
to try the call again or try again after driving a few miles into another cellular area.
See also:
Folding the Seatback
Notice: Folding a rear seat with the safety belts still fastened may cause damage to the seat or the safety belts. Always unbuckle the safety belts and return them to their normal stowed position befo ...
Electronic Range Select (ERS) Mode
ERS or manual mode allows for the selection of the range of gear positions. Use
this mode when driving down hill or towing a trailer to limit the top gear and vehicle
speed.
To use this feature:
...
Roof Rack System
WARNING
If something is carried on top of the vehicle that is longer or wider than the
roof rack—like paneling, plywood, or a mattress—the wind can catch it while the
vehicle is being driven. ...