DTC P1523: Throttle Closed Position Performance: Description
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition is on and the engine is off, and no accelerator pedal movement is detected, the Throttle Actuator Control (TAC) system will enter a battery saver mode. This mode removes power to the throttle actuator motor and allows the throttle blade to return to the rest position. The rest position is approximately 34 percent throttle position. DTC P1523 will set when the battery saver mode is active and the throttle plate does not return to the rest position.