The throttle actuator control (TAC) system uses vehicle electronics and components to calculate and control the position of the throttle blade. This eliminates the need for a mechanical cable attachment from the accelerator pedal to the throttle body. This system also performs the cruise control functions as well.

The TAC system components include, but are not limited to, the following:

The APP sensors and the throttle body assembly provide inputs to the ECM to ensure accurate calculations and control of the TAC system.

The APP sensor is mounted on the accelerator pedal assembly. The APP is actually 2 individual APP sensors within 1 housing. These are 2 separate signal, low reference, and 5-volt reference circuits. The APP sensor 1 voltage increases as the accelerator pedal is depressed. The APP sensor 2 voltage also increases as the accelerator pedal is depressed, but the voltage range for sensor 2 is approximately half of sensor 1.

The throttle body assembly consists of the throttle body, the throttle position (TP) sensors, and the throttle actuator motor. The throttle body functions similar to a conventional throttle body with the following exceptions:

Two separate signal circuits are used to connect the TP sensors and the ECM. The TP sensor 1 signal voltage increases as the throttle opens. The TP sensor 2 signal voltage decreases as the throttle opens.

The TAC module is the control center for the electronic throttle system. The TAC module is located within the ECM and is not serviceable separately. The ECM monitors the commanded throttle position and compares it to the actual throttle position. This is accomplished by monitoring the APP, TP, and other various sensors.

When the ECM detects a condition with the TAC system the ECM may enter a reduced engine power mode. Reduced engine power may cause one or more of the following conditions: