Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 Pontiac Montana SV6, 2007 Chevrolet Uplander, and 2007 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
The BCM does not receive an acknowledgment message from the RCDLR with 300 milliseconds of a second Programming Mode/Diagnostic Mode request.