AutoCodes – Buick – B3770 Buick

B3770 Buick 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 Buick 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 1,265

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

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

What does this mean?

What are the Possible Causes of the DTC B3770 Buick?

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 Buick?

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 Buick 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 B3770 Buick code?

Need more information on how to fix the B3770 Buick code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3770 Buick code diagnosed by a professional: Find a repair shop in your area

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 Buick Code

1. What does the OBDII code B3770 mean on a Buick?

The B3770 code indicates an issue with the Air Flow Control Feedback Circuit Actuator, where its operation is outside the expected range or performance parameters.

2. What are common symptoms of the B3770 code on a Buick?

Symptoms may include improper HVAC airflow, inability to control temperature or airflow direction, and a potential malfunction indicator light on the dashboard.

3. What causes the B3770 code to appear on a Buick?

Common causes include a faulty airflow control actuator, wiring issues in the feedback circuit, a stuck actuator, or a malfunctioning HVAC control module.

4. Can I drive my Buick with the B3770 code active?

Yes, you can drive the vehicle, but HVAC functionality may be limited or impaired, which could affect cabin comfort.

5. How do I diagnose the B3770 code on my Buick?

Diagnosis involves inspecting the airflow control actuator, checking for damaged or loose wiring, testing the feedback circuit, and scanning for additional HVAC-related codes.

6. How can I fix the B3770 code on a Buick?

Repairs may include replacing the airflow control actuator, repairing damaged wiring or connectors, or reprogramming or replacing the HVAC control module.

7. Is the B3770 code specific to any Buick models?

No, the B3770 code can appear on various Buick models equipped with an HVAC system that utilizes airflow control actuators.

8. How much does it cost to repair the B3770 code on a Buick?

Repair costs vary but commonly range from $150 to $500, depending on whether the actuator, wiring, or control module needs repair or replacement.

9. Can I fix the B3770 code on my Buick myself?

If you're experienced with automotive electrical systems, you may be able to replace the actuator or repair wiring yourself. Otherwise, professional diagnosis and repair are recommended.

10. Will resetting the code clear the B3770 issue on my Buick?

Resetting the code may temporarily clear it, but the issue will likely recur if the underlying problem is not resolved.