Throttle Actuator Control (TAC) Overview

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 is not limited to the following:

Each of these components interface together to ensure accurate calculations and control of the throttle position.

Accelerator Pedal Position (APP) Sensor

The APP sensor is mounted on the accelerator pedal assembly. The APP is actually 3 individual APP sensors within 1 housing. There are 3 separate signal, low reference, and 5-volt reference circuits. The APP sensor voltage increases as the accelerator pedal is depressed.

Throttle Body of the TAC Assembly

The throttle body for the TAC system is similar to a conventional throttle body with several exceptions. One exception being the use of a motor to control the throttle position instead of a mechanical cable. Another exception is the new design throttle position (TP) sensor. The TP sensor mounts on the side of the throttle body. The TP sensor is actually 2 individual TP sensors within 1 housing. Two separate signal, low reference, and 5-volt reference circuits are used to connect the TP sensors and the TAC module. The TP sensor signal voltage increases as the throttle opens.

Throttle Actuator Control (TAC) Module

The TAC module is the control center for the electronic throttle system. The module is also located on the accelerator pedal assembly. The TAC module and the PCM communicate via a dedicated redundant serial data circuit. The TAC module and the PCM monitor the commanded throttle position and compare commanded throttle position to the actual throttle position. This is accomplished by monitoring the APP and the TP sensor. These 2 values must be within a calibrated value of each other. The TAC module also monitors each individual circuit of the TP sensor and the APP to verify proper operation.

Battery Saver Mode

If the PCM detects the ignition ON for 10 seconds without the engine running, the PCM sends a message to the TAC module. At this time the TAC module will allow the throttle blade to return to the default position. This removes the draw that is present while holding the throttle blade at the calculated idle position.