B3770 Code: Meaning, Causes, and Symptoms | OBD2 Codes
B3770 – Air Flow Control Feedback Circuit Actuator Range/Performance
B3770 Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
B3770 Possible Causes
Faulty Mode Actuator,Mode Actuator harness is open or shorted,Mode Actuator circuit poor electrical connection,Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module
The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The module supplies a 5-volt source voltage to the potentiometer on the 5-volt reference circuit. The module supplies ground to the potentiometer through the low reference circuit. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The module converts the voltage value to a count value where 1-volt is approximately equal to 51 counts. The HVAC control module calibrates the travel range of the HVAC door actuators when it is initially powered by the battery positive voltage circuit. During calibration, the module commands the actuators in each direction until door travel is stopped. The module stores the minimum door positions and the maximum door positions of each actuator into memory. The total travel range is calculated by subtracting the minimum door position from the maximum door position.