DTC P2105: Throttle Actuator Control System - Forced Engine Shutdown: 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.

The Throttle Actuator Control (TAC) module contains a direct current actuator motor controlled by the ECM used to move the throttle plate (in either direction) and two throttle position sensors to determine throttle plate position. The throttle plate is held at a 7 percent rest position to a mechanical stop by a constant force return spring. This spring will hold the throttle plate to the stop when there is no current flowing to the actuator motor. There is another return spring, which creates constant force on the throttle plate only when the throttle plate is moved towards the full closed position. The ECM will monitor both the actuator motor and TP sensors for circuit faults as well as check to make sure both springs can return the throttle to the 7 percent position no matter where the throttle plate remains. The ECM has the ability to force the engine to the idle state if it detects an error in the throttle control system that is out of controllable limits deemed unsafe. This protection is used when the ECM cannot rely on throttle position inputs, if the throttle position sensors are indicating that the throttle is too far open for safe driver operation or if an error is occurring with the throttle actuator control system algorithm. DTC P2105 will set if the ECM determines an error is occurring in the throttle actuator control system that it determines to be out of controllable limits.