Conditions for Setting the DTC: P0603
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 a reset error of the internal software that operates the throttle actuator control (TAC) system, during the shut down path test. The condition exists, then a 5 second delay for MIL ON.