AutoCodes – GMC – B0408 2017 GMC Sierra

B0408 2017 GMC Sierra Code - Main Temperature Control Circuit

Quick Answer

Stepper motors are used for temperature regulation, air distribution control and recirculation door control. Common causes include Faulty Air Temperature Actuator, Air Temperature Actuator harness is open or shorted, Air Temperature Actuator circuit poor electrical connection. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

What it means: B0408 2017 GMC Sierra indicates Main Temperature Control Circuit.
Common causes: Common causes include Faulty Air Temperature Actuator, Air Temperature Actuator harness is open or shorted, Air Temperature Actuator circuit poor electrical connection.
Severity: Low - monitor the vehicle and repair when practical.
Can I drive?: The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.

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Code Popularity 242

How popular is this code, among other codes? Low

Repair Importance Level

Low (Monitor) (1 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

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

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B0408 2017 GMC Sierra Description

Stepper motors are used for temperature regulation, air distribution control and recirculation door control. With the switches and dials on the HVAC controls, air temperature door position, mode door position and recirculation door position can be selected. The selected values are passed to the Heating, Ventilation, and Air Conditioning (HVAC) Control Module via serial data. The HVAC control module supplies a 12 V reference voltage to the stepper motors and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motors move the appropriate doors into the calculated positions, in order to reach the desired positions.

OBDII Code B0408 2017 GMC Sierra - Main Temperature Control Circuit - AutoCodes.com — B0408 2017 GMC Sierra Code - Main Temperature Control Circuit

What does this mean?

What are the Possible Causes of the DTC B0408 2017 GMC Sierra?

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

How to Fix the DTC B0408 2017 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 does this mean?

Code Tech Notes

B0413:02 Main Temperature Control Circuit Short to Ground
B0413:05 Main Temperature Control Circuit Short to Battery or Open
B0413:61 Main Temperature Control Circuit Actuator Stuck Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0408 2017 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 B0408 2017 GMC Sierra 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 B0408 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code B0408 in a 2017 GMC Sierra?

Common symptoms include issues with the main temperature control not functioning properly, inconsistent cabin temperature, and potential lack of control over the heating and cooling system.

2. What does the OBDII code B0408 for the main temperature control circuit indicate in a 2017 GMC Sierra?

This code indicates a malfunction in the main temperature control circuit, which can lead to problems with regulating the interior temperature of the vehicle.

3. What are the possible causes of OBDII code B0408 in a 2017 GMC Sierra?

Possible causes include a faulty main temperature control module, wiring issues, a blown fuse, or a malfunctioning blend door actuator.

4. How can I diagnose the main temperature control circuit issue related to OBDII code B0408 in my 2017 GMC Sierra?

Diagnosis involves using a scan tool to retrieve the specific code, inspecting the main temperature control module and associated wiring for damage, and testing the blend door actuator for proper functionality.

5. What are some basic repair tips for resolving OBDII code B0408 in a 2017 GMC Sierra?

Basic repair tips include checking and replacing any blown fuses related to the main temperature control circuit, ensuring all wiring connections are secure, and replacing the main temperature control module if necessary.

6. Can OBDII code B0408 in a 2017 GMC Sierra be fixed without professional help?

While some basic troubleshooting and repairs can be done by DIY enthusiasts, it is recommended to consult a professional mechanic for accurate diagnosis and repair of the main temperature control circuit issue.

7. Is it safe to continue driving a 2017 GMC Sierra with OBDII code B0408?

It is not recommended to drive the vehicle with unresolved OBDII code B0408, as it can lead to discomfort due to temperature control issues and potentially affect other components of the heating and cooling system.

8. How much can I expect to pay for repairing OBDII code B0408 in a 2017 GMC Sierra?

The cost of repairing OBDII code B0408 can vary depending on the specific cause of the issue, but it typically ranges from a few hundred to over a thousand dollars, including parts and labor.

9. Can resetting the OBDII system clear the B0408 code in a 2017 GMC Sierra?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue with the main temperature control circuit is not addressed, the code is likely to reappear. It's best to diagnose and fix the root cause.

10. How can regular maintenance help prevent OBDII code B0408 from appearing in a 2017 GMC Sierra?

Regular maintenance, such as checking and replacing cabin air filters, inspecting wiring connections, and ensuring proper functioning of the heating and cooling system components, can help prevent issues leading to OBDII code B0408.