AutoCodes – GMC – B3747 GMC

B3747 GMC Code - Air Flow Control 1 Feedback Circuit

Quick Answer

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC actuators to regulate the airflow and temperature through the HVAC system. Common causes include Faulty Defrost Actuator, Defrost Actuator harness is open or shorted, Defrost 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: B3747 GMC indicates Air Flow Control 1 Feedback Circuit.
Common causes: Common causes include Faulty Defrost Actuator, Defrost Actuator harness is open or shorted, Defrost 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 408

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 B3747 GMC Description

The Heating, Ventilation, and Air Conditioning (HVAC) Control Module controls the HVAC actuators to regulate the airflow and temperature through the HVAC system. The actuators are 2 wire, bi-directional electric motors that share the same common control circuit. When the operator adjusts the actuators, the control module can only operate one actuator at a time due to the shared common control circuit. The control circuits use either a 0 or 12-volt value to co-ordinate the actuator movement. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.
The HVAC control module determines the door position by counting motor pulses on one of the control circuits. The HVAC control module converts the pulses to counts with a range of 0-255 counts.
When a calibration or recalibration procedure is performed, the HVAC control module calculates the door travel range. The HVAC control module compares the total number of pulses to calibrated limits. If the total pulse count is less than or equal to the maximum calibrated limited and more that or equal to the minimum calibrated limit, then the calibration is considered successful.

OBDII Code B3747 GMC - Air Flow Control 1 Feedback Circuit - AutoCodes.com — B3747 GMC Code - Air Flow Control 1 Feedback Circuit

What does this mean?

What are the Possible Causes of the DTC B3747 GMC?

Faulty Defrost Actuator
Defrost Actuator harness is open or shorted
Defrost Actuator circuit poor electrical connection
Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module

How to Fix the DTC B3747 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 B3747 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 B3747 GMC code?

Need more information on how to fix the B3747 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3747 GMC 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 B3747 GMC Code

1. What are common symptoms of OBDII code B3747 GMC (Air Flow Control 1 Feedback Circuit)?

- Common symptoms include poor engine performance, rough idle, stalling, and decreased fuel efficiency.

2. What are the possible causes of OBDII code B3747 GMC?

- Possible causes include a faulty air flow control sensor, wiring issues, poor electrical connections, or a problem with the engine control module.

3. How can I diagnose OBDII code B3747 GMC?

- Diagnosis typically involves using a scan tool to read the code, checking the air flow control sensor and related wiring, and testing for proper sensor operation.

4. What should I check first when troubleshooting OBDII code B3747 GMC?

- Start by checking the air flow control sensor for any visible damage or signs of wear. Ensure the sensor is securely connected and the wiring is intact.

5. Can I drive my vehicle with OBDII code B3747 GMC?

- It is not recommended to drive with this code present, as it can lead to further engine damage and decreased performance. It is best to address the issue promptly.

6. How do I repair OBDII code B3747 GMC?

- Repair may involve replacing the air flow control sensor, repairing any damaged wiring, ensuring proper electrical connections, or reprogramming the engine control module.

7. Will resetting the OBDII code B3747 GMC make it go away permanently?

- Simply resetting the code may temporarily clear the warning light, but if the underlying issue is not addressed, the code is likely to reappear.

8. Are there any DIY fixes for OBDII code B3747 GMC?

- DIY fixes may include checking and cleaning electrical connections, inspecting for loose wires, or replacing the air flow control sensor if accessible.

9. How much does it cost to repair OBDII code B3747 GMC at a mechanic?

- Repair costs can vary depending on the exact cause of the code, but expect to pay for parts and labor, which could range from $100 to $500 or more.

10. How long does it take to fix OBDII code B3747 GMC?

- The repair time can vary based on the specific issue, but a skilled mechanic can typically diagnose and fix the problem within a few hours to a day.