AutoCodes – GMC – B3770 GMC

B3770 GMC Code - Air Flow Control Feedback Circuit Actuator Range/Performance

Quick Answer

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC door actuators to regulate the airflow through the HVAC system. 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: B3770 GMC indicates Air Flow Control Feedback Circuit Actuator Range/Performance.
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 5,805

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 15, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3770 GMC Description

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The module supplies a 5-volt source voltage to the potentiometer on the 5-volt reference circuit. The module supplies ground to the potentiometer through the low reference circuit. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The module converts the voltage value to a count value where 1-volt is approximately equal to 51 counts. The 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.

OBDII Code B3770 GMC - Air Flow Control Feedback Circuit Actuator Range/Performance - AutoCodes.com — B3770 GMC Code - Air Flow Control Feedback Circuit Actuator Range/Performance

What does this mean?

What are the Possible Causes of the DTC B3770 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 B3770 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 B3770 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.

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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 B3770 GMC Code

1. What are the common symptoms of OBDII code B3770 GMC?

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

2. What does the OBDII code B3770 GMC indicate?

- The code B3770 indicates a problem with the Air Flow Control Feedback Circuit Actuator's range or performance in a GMC vehicle.

3. What are some possible causes of OBDII code B3770 GMC?

- Possible causes of this code may include a faulty air flow control feedback circuit actuator, wiring issues, or a problem with the control module.

4. How can I diagnose the OBDII code B3770 GMC?

- Diagnosing this code typically involves using a scan tool to retrieve the code, performing a visual inspection of related components, and testing the actuator and circuit for proper operation.

5. Can I drive my GMC with the OBDII code B3770 present?

- It is not recommended to drive your GMC with this code present, as it can lead to further engine damage and potential safety hazards. It's best to address the issue promptly.

6. How can I repair OBDII code B3770 GMC?

- Repairing this code may involve replacing the faulty air flow control feedback circuit actuator, repairing any damaged wiring, or reprogramming the control module.

7. Are there any quick tips to troubleshoot OBDII code B3770 GMC?

- Quick tips for troubleshooting this code include checking for loose or damaged wiring, ensuring proper connection of the actuator, and clearing the code to see if it returns.

8. Is OBDII code B3770 GMC a serious issue?

- While the severity of this code can vary, it is important to address it promptly to prevent further damage to engine components and ensure optimal vehicle performance.

9. Can I reset the OBDII code B3770 GMC on my own?

- You can attempt to reset the code using a scan tool or by disconnecting the vehicle's battery for a few minutes. However, it's crucial to address the underlying issue causing the code.

10. How much does it cost to fix OBDII code B3770 GMC?

- The cost of fixing this code can vary depending on the specific issue causing it, the parts needed for repair, and whether you choose to perform the repair yourself or take it to a mechanic.