B0408 GMC Possible Causes
- Faulty Air Temperature Actuator
- Air Temperature Actuator harness is open or shorted
- Air Temperature Actuator circuit poor electrical connection
- Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module
How do I fix code B0408 GMC
Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
Cost of diagnosing the B0408 GMC code
Labor: 1.0The cost of diagnosing the B0408 GMC code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
B0408 GMC Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B0408 GMC MeaningStepper motors are used for temperature regulation, air distribution control and recirculation door control. With the switches and dials on the HVAC controls, air temperature door position, mode door position and recirculation door position can be selected. The selected values are passed to the Heating, Ventilation, and Air Conditioning (HVAC) Control Module via serial data. The HVAC control module supplies a 12 V reference voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors move the appropriate doors into the calculated positions, in order to reach the desired positions.
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