Diagnostic Aids

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

An open on the key in ignition switch signal circuit will intermittently cause the column not to unlock.
Disconnecting or opening the steering column lock feedback circuit will cause the BCM to enter a Fail Enable Standby mode. The steering column will remain inoperative until the Fail Enable Standby mode is cleared. To clear this mode, disconnect the BCM1 & IPC fuse in the I/P fuse block for 15 seconds.

Fig 1: Diagnostic System Check - Service Column Lock Indicator Always On
Courtesy of GENERAL MOTORS CORP.