Throttle Body: Description and Operation

THROTTLE BODY ASSEMBLY

Throttle Body Assembly:

The throttle body functions similar to a conventional throttle body with the following exceptions:
- An electric motor opens and closes the throttle valve.
- The TAC module is an integral part of the throttle body assembly.
- The throttle valve is spring loaded and the default position is slightly open.
- There are 2 individual throttle position (TP) sensors integral to the TAC module cover.

The TP sensors are used to determine the throttle plate angle. The TP sensors provide the TAC module with a signal voltage proportional to throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. TP sensor 1 determines the actual throttle valve position. TP sensor 2 provides a backup value for TP sensor 1.

THROTTLE BODY ASSEMBLY

Throttle Body Assembly:

The throttle body contains a throttle valve that controls the amount of air entering the engine. The throttle valve is opened and closed by the throttle actuator control (TAC) motor. The TAC motor is an integral part of the TAC module assembly (2) mounted on the side of the throttle body. The TAC motor is controlled by commands from the powertrain control module (PCM), passed to the module circuitry through a dedicated serial data line. The TAC module also contains two throttle position (TP) sensors, TP sensor 1 and TP sensor 2. For detailed information on the operation of the TAC system refer to Throttle Actuator Control (TAC) System Description.

In order to prevent cold weather icing and stabilize cold weather performance, the throttle body is warmed by engine coolant (4). The manifold absolute pressure (MAP) sensor (6) is located on top of throttle body.