B3764

Steps 1-3:

Steps 4-13:

CIRCUIT DESCRIPTION
The auxiliary mode actuator is an electronic device that incorporates a stepper motor and feedback potentiometer. The rear auxiliary HVAC control module controls the auxiliary 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 rear auxiliary HVAC control module. The rear auxiliary 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 rear auxiliary HVAC control module calculates the mode actuator travel range. The rear auxiliary HVAC control module commands the actuator through it's full range. The rear auxiliary 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 rear auxiliary 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 rear auxiliary 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.

CONDITIONS FOR SETTING THE DTC
- Auxiliary mode actuator position signal is less than 5 counts.
- Auxiliary 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 auxiliary rear HVAC control module 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
- 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.
- A short to voltage on the 5 volt reference circuit or lower mode valve position sensor signal circuit of the auxiliary mode actuator will set a DTC B0429 along with DTC B3764. Refer to DTC B0429 Air Mix Door #3 Range Error.B0429