Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The transponder value is valid and matches the value stored in the TDM memory.
The transponder calculation to the challenge from the TDM does not match the TDM calculation.