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:
When to Add Engine Oil
If the oil is below the cross-hatched area at the tip of the dipstick, add 1 L (1 qt) of the recommended oil and then recheck the level. See “Selecting the Right Engine Oil” in this section for ...
Other ITBC-Related DIC Messages
In addition to displaying TRAILER GAIN and TRAILER OUTPUT through the DIC, trailer connection and ITBC system status are displayed on the DIC.
TRAILER CONNECTED: This message will be briefly displaye ...
Battery Voltage and Charging Messages
BATTERY LOW START VEHICLE
When the vehicle’s battery is severely discharged, this message will display and four chimes will sound. Start the vehicle immediately. If the vehicle is not started and t ...