B0428 GMC Possible Causes
- Faulty Auxiliary Air Temperature Actuator
- Auxiliary Air Temperature Actuator harness is open or shorted
- Auxiliary Air Temperature Actuator circuit poor electrical connection
- Faulty Auxiliary Heating, Ventilation, and Air Conditioning (HVAC) Control Module
First diagnose B0428 GMC code
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 terminals.
Cost of diagnosing the B0428 GMC code
Labor: 1.0The cost of diagnosing the B0428 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.
B0428 GMC Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
B0428 GMC MeaningThe Auxiliary Heating, Ventilation, and Air Conditioning (HVAC) actuators are a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Low reference, 5-volt reference, position signal, and 2 control circuits enable the actuator to operate. The control circuits use either a 0 or 12 volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The auxiliary HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction. When the actuator shaft rotates, the potentiometers adjustable contact changes the door position signal between 0-5 volts. This signal then is converted into a count value where as 1 volt will equal 51 counts.
The auxiliary 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.
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