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The TACM monitors the accelerator pedal position through the two APP sensors and forwards this signal to the PCM via
a dedicated serial data line. The PCM processes this information along with other system sensor inputs to command the
throttle plate to a certain position. This throttle position request is sent back the TACM along the same serial data line,
and the TACM sends a pulse width modulated signal to the throttle body.
A direct current motor called the throttle actuator control motor controls the throttle plate. The TACM can operate this
motor in the forward or reverse direction by controlling battery voltage and/or ground to two internal drivers. When there
is no current flowing to the actuator motor, the throttle plate is held at a rest position of 7 percent open using a constant
force return spring.
The TACM monitors the throttle plate angle through two TP sensors. Using this information, the TACM can precisely
adjust the throttle plate.
The TACM performs diagnostics that monitor the voltage levels of both APP sensors, both TP sensors and the throttle
actuator control motor circuit. It also monitors the spring return rate. These diagnostics are performed at different times
based on whether the engine is running, not running, or whether the TACM is currently in a throttle body relearn
procedure. This information is sent to the PCM for external diagnosis purposes.
Two sensors within the accelerator pedal assembly and throttle body assembly are used to provide redundancy. If a
malfunction is detected, the throttle plate is moved to a pre-determined position.
Every ignition cycle, the TACM performs a quick throttle return spring test to ensure the throttle plate can return to the 7
percent rest position from the 0 percent position. This is to ensure that the throttle plate can be brought to the rest
position in case of an actuator motor circuit failure.
The VZ Gen III is the only one that does it. The VY was cable actuated.Which Gen 3 PCM drives an electronic throttle body?