Conditions for Clearing the MIL/DTC
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The theft deterrent control module clears the current status of the DTC when it does not see the Learn Coded Key setting as on. The DTC will still be retrieved as current until the ignition switch is cycled. The DTC will become a history DTC at that time.