AutoCodes – GMC – B374A 2018 GMC Sierra

B374A 2018 GMC Sierra Code - Air Flow Control Position Feedback Circuit

Quick Answer

Doors in the Heating, Ventilation, and Air Conditioning (HVAC) case assembly are used to control airflow. Common causes include Faulty Mode Actuator, Mode Actuator harness is open or shorted, Mode Actuator circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B374A 2018 GMC Sierra indicates Air Flow Control Position Feedback Circuit.
Common causes: Common causes include Faulty Mode Actuator, Mode Actuator harness is open or shorted, Mode Actuator circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 249

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 29, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B374A 2018 GMC Sierra Description

Doors in the Heating, Ventilation, and Air Conditioning (HVAC) case assembly are used to control airflow. The HVAC control module operates the doors using actuators, with one actuator being used for each door. The system has the following air control doors and associated actuators: mode, left and right temperature, and recirculation. When equipped with auxiliary HVAC controls 2 additional actuators are added for auxiliary (rear) mode and temperature.
Each actuator used in the system is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. The five circuits are low reference, 5 V reference, actuator position signal, and two control circuits. The control circuits use either ground or 12 V value to coordinate the actuator movement. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 V. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
When the actuator shaft rotates, the potentiometer's sliding contact changes the door position signal between 0-5 V. The HVAC control module converts the voltage signal to counts. The total range of the counts is 0-1024, with an operating range between 20-1000. The actual operating range of an actuator is determined during calibration. During calibration, the actuator is moved through its full range of travel, and the module stores the minimum and maximum value. Based on the desired system operation, the module sets a commanded, or targeted, value for the actuators. The control circuits are operated to move the door to the required position, and the changing position signal is sent to the module. Once the actual position signal and the commanded value are the same, the module ceases operating the control circuits and the actuator (and door) remains in the desired position.

OBDII Code B374A 2018 GMC Sierra - Air Flow Control Position Feedback Circuit - AutoCodes.com — B374A 2018 GMC Sierra Code - Air Flow Control Position Feedback Circuit

What does this mean?

What are the Possible Causes of the DTC B374A 2018 GMC Sierra?

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

How to Fix the DTC B374A 2018 GMC Sierra?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B374A 2018 GMC Sierra code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B374A 2018 GMC Sierra code?

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Need Help with the Code?

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B374A 2018 GMC Sierra Code

1. What are common symptoms of OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Common symptoms may include poor engine performance, rough idling, reduced fuel efficiency, and possibly stalling.

2. What are some possible causes of OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Potential causes could be a faulty air flow sensor, wiring issues, a vacuum leak, or a malfunctioning electronic control module (ECM).

3. How can I diagnose OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Diagnosis typically involves using an OBDII scanner to retrieve the code, inspecting the air flow sensor and its wiring, checking for vacuum leaks, and testing the ECM.

4. Can I continue driving my 2018 GMC Sierra with OBDII code B374A related to the Air Flow Control Position Feedback Circuit?

- It is not recommended to drive with this code present, as it can lead to further damage and potentially unsafe driving conditions.

5. How can I repair OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Repair methods may include replacing the air flow sensor, repairing or replacing damaged wiring, fixing any vacuum leaks, or reprogramming the ECM.

6. Will resetting the OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit solve the issue?

- Resetting the code may temporarily clear the warning light, but it will not fix the underlying problem causing the code to trigger.

7. Is it possible to prevent OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Regular maintenance, such as keeping the air filter clean and checking for vacuum leaks, can help prevent issues that may trigger this code.

8. Can a DIY enthusiast repair OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Depending on the individual's skill level, some repairs related to this code can be done at home, but more complex issues may require professional assistance.

9. Are there any recalls or service bulletins related to OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- It is advisable to check with your local GMC dealership or visit the manufacturer's website to see if there are any relevant recalls or service bulletins regarding this code.

10. How much can I expect to pay to repair OBDII code B374A in a 2018 GMC Sierra related to the Air Flow Control Position Feedback Circuit?

- Repair costs can vary depending on the specific issue causing the code, but it is recommended to obtain a diagnostic from a qualified mechanic to determine the exact cost.