Conditions for Setting the DTC: P2100
WARNING: This page is about a different car, the 2009 Pontiac Torrent and 2009 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
The ECM detects the output circuit for the TAC motor is open, shorted to ground, or shorted to a voltage. The condition exists, then a 5 second delay for MIL ON.