AutoCodes – GMC – B374A GMC

B374A GMC 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 GMC 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 3,232

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

What does this mean?

What are the Possible Causes of the DTC B374A GMC?

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 GMC?

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 GMC 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 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

B374A 2014 GMC Sierra — Air Flow Control Position Feedback Circuit
B374A 2015 GMC Sierra — Air Flow Control Position Feedback Circuit
B374A 2016 GMC Sierra — Air Flow Control Position Feedback Circuit
B374A 2017 GMC Sierra — Air Flow Control Position Feedback Circuit
B374A 2018 GMC Sierra — Air Flow Control Position Feedback Circuit

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 GMC Code

1. What are the common symptoms of OBDII code B374A GMC (Air Flow Control Position Feedback Circuit)?

- Common symptoms include poor engine performance, rough idling, stalling, and potential decrease in fuel efficiency.

2. What are the possible causes of OBDII code B374A GMC?

- The code B374A GMC can be triggered by issues such as a faulty air flow control position sensor, wiring issues, or a defective ECM.

3. How can I diagnose the OBDII code B374A GMC?

- Diagnosis typically involves using an OBDII scanner to read the code, checking the air flow control position sensor and its wiring for any visible damage, and testing the sensor's functionality.

4. Can a dirty air filter trigger the OBDII code B374A GMC?

- While a dirty air filter can affect engine performance, it is unlikely to directly trigger the B374A code. However, a restricted air filter can indirectly impact the air flow control position feedback circuit.

5. Is it safe to continue driving with the OBDII code B374A GMC active?

- It is generally not recommended to drive with the B374A code present, as it can lead to further engine issues and potential damage over time. It is advisable to address the underlying problem promptly.

6. How can I repair the OBDII code B374A GMC?

- Repairing the B374A code involves fixing or replacing the faulty air flow control position sensor, addressing any wiring issues, and clearing the code with an OBDII scanner.

7. Can I reset the OBDII code B374A GMC without fixing the underlying issue?

- While you can clear the code temporarily, it will likely reappear if the root cause is not addressed. It is crucial to fix the underlying problem to prevent the code from coming back.

8. Are there any DIY repair tips for addressing the OBDII code B374A GMC?

- DIY repair tips may include checking and cleaning the sensor's connectors, inspecting the wiring for any visible damage, and ensuring proper sensor alignment during replacement.

9. How much does it cost to fix the OBDII code B374A GMC at a repair shop?

- The cost of fixing the B374A code can vary depending on the extent of the issue, the labor rates of the repair shop, and the cost of parts. It is advisable to get a few quotes from different shops.

10. Can a mechanic help me diagnose and repair the OBDII code B374A GMC?

- Yes, a qualified mechanic can diagnose the issue using specialized tools, pinpoint the exact cause of the code, and perform the necessary repairs to resolve the B374A GMC fault.