B12B1 Code: Meaning, Causes, and Symptoms | OBD2 Codes
B12B1 – Front Blower Motor PWM Drive Circuit Shorted To Voltage
B12B1 Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
B12B1 Possible Causes
Faulty Blower Motor Speed Control Module,Blower Motor Speed Control Module harness is open or shorted,Blower Motor Speed Control Module circuit poor electrical connection,Faulty Electronic Automatic Temperature Control (EATC) Module
Under normal operation, the blower motor relay coil receives ground from the Electronic Automatic Temperature Control (EATC) Module through the circuit. The coil receives ignition voltage through the circuit. Voltage is supplied to the relay switch contact. When the relay coil is energized, the voltage is delivered to the blower motor and the blower motor speed control module through the circuit. Ground for the motor is provided through the circuit from the blower speed control module. Ground for the blower motor speed control module is provided by the circuit. The EATC module sends a Pulse Width Modulation (PWM) signal to the Blower Motor Speed Control Module through a circuit to control the blower speed.