B12B2 Code: Meaning, Causes, and Symptoms | OBD2 Codes

B12B2 – Front Blower Motor PWM Drive Circuit Open or Shorted to Ground

 

B12B2 Possible Symptoms

 

Engine Light ON (or Service Engine Soon Warning Light)

 

B12B2 Possible Causes

 

Faulty Front Blower Motor Fuse,Faulty Front Blower Motor Relay,Front Blower Motor Relay harness is open or shorted,Front Blower Motor Relay circuit poor electrical connection,Faulty Front Blower Motor,Faulty Electronic Manual Temperature Control (EMTC) Module

 

B12B2 Description

 

Under normal operation, the blower motor relay coil receives ignition voltage through the circuit. The coil receives ground from the Electronic Manual Temperature Control (EMTC) Module through the circuit if any function selector position but OFF is selected. Voltage is supplied to the relay switch contact. When the relay coil is energized, the voltage is delivered to the blower motor through the circuit. Ground for the blower motor is provided through the circuit from the blower resistor or the blower switch (HI). The blower resistor and blower switch are grounded through the circuit. The module senses no voltage on the blower motor control Pulse Width Modulation (PWM) circuit, indicating an open or a short directly to ground.