Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
You will want to make sure that the brake lights are working and it's not something simple like a fuse. However, there has been a service bulletin on the BTSI wiring harness for that type of concern, here is what it states,
Bulletin No.: 08-07-30-007B
Date: June 08, 2009
Subject: EI08045 - Key Cannot Be Removed from Ignition with Gear Selector in Park, Shifter Cannot Be Moved from Park Position (Repair/Reroute Brake Transmission Shift Interlock (BTSI) Solenoid Harness)
Some customers may comment on either of the following conditions:
This condition may be caused by an incorrectly routed brake transmission shift interlock (BTSI) solenoid harness which can make it difficult to install. In some instances, the wiring looms are tangled, causing stress on the wires in the connector at the BTSI. If the BTSI harness is routed incorrectly, it may also result in a wire pinching issue.
Inspection/Routing and Repair of the BTSI Wiring Harness/Connector
BTSI Wiring Harness Incorrectly Routed
BTSI Wiring Harness Routed Correctly
Examining the BTSI wiring harness is above my abilities. Key inserts, and car starts up normally. All other functions (lights, radio, windows, heat, wipers, etc.) appear okay. Emergency brake applied and released okay. Panel warning about ice (and a low pressure tire.) Steering turns full left & right.
Are we looking at a tow to a GM garage?
Thank you. Looks like that requires tools and a better place to work than my driveway in 15 degree weather. I'll accept your answer.