B3761
CIRCUIT DESCRIPTIONThe mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The HVAC control module controls the mode door position by sending a control signal to the actuator. The signal's value is dependent upon the desired mode selected by the vehicle occupants. As the actuator moves, the potentiometer produces the actual door position signal that is sent to the HVAC control module. The HVAC control module continues to command the actuator to move until the desired and actual values are equal. The door directs airflow through the outlets as selected by the vehicles occupants.
After a calibration or recalibration procedure is performed, the HVAC control module calculates the mode actuator travel range. The HVAC control module commands the actuator through it's full range. The HVAC control module stores the learned minimum and maximum position values. The travel range value is calculated by subtracting the minimum and maximum position values. Then the HVAC control module compares the travel range, minimum and maximum values to calibrated value ranges. If the travel range value is less than or equal to the maximum calibrated limit and greater than or equal to the minimum calibrated limit, then the calibration is considered successful. The HVAC control module continuously compares the actual actuator position to the calibrated minimum and maximum position values.
CONDITIONS FOR RUNNING THE DTC
^ The ignition is ON.
^ Ignition voltage is between 9-16 volts. The HVAC control module keep alive memory battery power must be interrupted to run the range check (recalibration procedure).
CONDITIONS FOR SETTING THE DTC
^ Mode actuator position signal is less than 5 counts.
^ Mode actuator position signal is more than 250 counts.
^ The recirculation actuators total travel range (min-max) is less than or greater than the calibrated limits.
ACTION TAKEN WHEN THE DTC SETS
^ The DTC is stored in DTC information.
^ The HVAC control module will continue to make use of whatever travel range is still available.
CONDITIONS FOR CLEARING THE DTC
^ If the HVAC control no longer detects a failure, then the DTC will become history.
^ The history DTC will clear after 50 ignition cycles without a failure.
^ The DTC can be cleared with a scan tool.
DIAGNOSTIC AIDS
^ A damaged or broken mode door and or actuator can cause this DTC to set.
^ The range fault can only be detected following a check of the actuator travel range. The actuator travel range check (recalibration procedure) can only be initiated by disrupting power to the HVAC control module.
TEST
Steps 1-3:
Steps 4-13:
