Are you using a TECH II? If not, that's what you need to be using, or something similar..
Complete the following procedure, using a scan tool, in order to properly set up communication:
1. At the Main Menu screen, select: Diagnostics.
2. At the Vehicle Identification screen, select the following options:
* Model Year
* Passenger Car
3. At the System Selection Menu screen, select: Body.
4. At the Vehicle Identification screen, select the appropriate model.
5. At the Body screen, select: Radio.
6. At the Radio screen, select: Special Functions.
7. At the Special Functions screen, select: Radio Setup.
8. At the Radio Setup screen, press ENTER. The following test will set up a new or existing radio.
9. Verify that the scan tool displays "Test in Progress."
10. Verify that the scan tool displays "Test Completed Successfully."
11. Press EXIT on the scan tool and cycle the ignition.