Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The BCM will inspect for a tamper code when the ignition switch rotates from ON to CRANK and will continue to monitor the signal during the engine running period.
The BCM is reading a tamper code from the Passlock™ sensor for longer than 1.0 seconds.