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:
Underbody Maintenance
Use plain water to flush dirt and debris from the vehicle's underbody.
Your dealer or an underbody car washing system can do this. If not removed, rust and corrosion can develop. ...
Replacing Brake System Parts
The braking system on a vehicle is complex. Its many parts have to be of top quality and work well together if the vehicle is to have really good braking. The vehicle was designed and tested with top- ...
Battery Replacement
Replace the battery if the REPLACE BATTERY IN REMOTE KEY message displays in
the DIC. See ЃgReplace Battery in Remote KeyЃh under Key and Lock Messages on page
5.29.
The battery is not recharge ...