B3764

DTC B3764












CIRCUIT DESCRIPTION
The auxiliary mode actuator is an electronic device that incorporates a stepper motor and a feedback potentiometer. The HVAC control module determines the position of the auxiliary mode actuator that is based on the voltage from the potentiometer. When the keep alive RAM memory, the battery positive voltage circuit, of the HVAC control module is interrupted, the module will calibrate the actuators. The HVAC control module performs a travel range comparison of the determined values of the actuator to the calibrated values within the HVAC control module. If the determined range does not equal the calibrated expected range, the actuator will be considered not calibrated, and the DTC will set. The HVAC control module will also perform a continuous test on the current feedback value. If the feedback value does not fall within the calibrated range, the DTC will set.

CONDITIONS FOR RUNNING THE DTC
-> The ignition is ON.
-> Ignition voltage is between 9-16 volts.
-> The battery positive voltage circuit, which provides keep alive RAM memory power, of the HVAC control module must be interrupted in order to run the recalibration. This includes disconnecting the battery, removal of the Radio fuse and disconnecting the HVAC control module.

CONDITIONS FOR SETTING THE DTC
-> The position signal of the auxiliary mode door is out of the range 0.09-4.0 volts (5-250 counts).
-> The total travel range of the auxiliary mode actuator falls without the calibrated limits.

ACTION TAKEN WHEN THE DTC SETS
-> The HVAC control module will continue to make use of whatever travel range is still available.
-> Each time the ignition switch is turned ON, the HVAC control module retests the actuator travel range.

CONDITIONS FOR CLEARING THE DTC
-> If the HVAC control no longer detects a condition, then the DTC will become history.
-> The history DTC will clear after 50 ignition cycles without a condition.
-> The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
-> The range fault can only be detected following a recalibration. The recalibration can only be initiated by removing the battery positive voltage circuit to the HVAC control module.
-> The calibration limit is 64-216 counts. An actual range below this limit suggests an obstruction, something stuck in the door which limits travel. An actual range above this limit suggests an excessive travel condition, damaged, or missing foam seals.
-> A damaged auxiliary mode door or a damaged actuator can cause this DTC to set.
-> An intermittent short to ground on the HVAC class 2 serial data circuit can set this DTC. Recalibrate actuators and test system.
-> If the condition is not present, refer to Testing for Intermittent and Poor Connections.