LaCrosse V6-3.8L (2009)
throttle actuator control (TAC) module through a dedicated serial data line.
Modes of Operation
Normal Mode
During the operation of the throttle actuator control (TAC) system, several modes or functions are considered normal. The following modes may be
entered during normal operation:
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Minimum pedal value-At key-up, the powertrain control module (PCM) updates the learned minimum pedal value.
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Minimum throttle position (TP) values-At key-up, the PCM updates the learned minimum throttle position value. In order to learn the minimum
throttle position value, the throttle blade is moved to the closed position.
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Ice break mode-If the throttle is not able to reach a predetermined minimum throttle position, the ice break mode is entered. During the ice break
mode, the PCM commands the maximum pulse width several times to the throttle actuator motor in the closing direction.
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Battery saver mode-After a predetermined time without engine RPM, the PCM commands the battery saver mode. During the battery saver mode,
the TAC module removes the voltage from the motor control circuits, which removes the current draw used to maintain the idle position and
allows the throttle to return to the spring loaded default position.
Reduced Engine Power Mode
When the PCM detects a condition with the TAC system, the PCM may enter a reduced engine power mode. Reduced engine power may cause one or
more of the following conditions:
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Acceleration limiting-The PCM will continue to use the accelerator pedal for throttle control, however the vehicle acceleration is limited.
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Limited throttle mode-The PCM will continue to use the accelerator pedal for throttle control however the maximum throttle opening is limited.
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Throttle default mode-The PCM will turn off the throttle actuator motor and the throttle will return to the spring loaded default position.
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Forced idle mode-The PCM will perform the following actions:
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Limit engine speed to idle by positioning the throttle, or by controlling the fuel and spark if the throttle is turned off.
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Ignore the accelerator pedal input.
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Engine shutdown mode-The PCM will disable fuel and de-energize the throttle actuator.
