Engine-Codes.com
Engine-Codes – GMC – B138A GMC

B138A GMC Code - Control Module Voltage Reference Output Circuit

Quick Answer

The B138A GMC code indicates a problem with the Control Module Voltage Reference Output Circuit in the vehicle. Common causes include Wiring Issues: Faulty or damaged wiring in the control module voltage reference output circuit can disrupt the voltage supply and trigger the B138A code, Connector Problems: Loose or corroded connectors can interfere with the proper transmission of voltage signals, leading to circuit malfunctions, Control Module Failure: A malfunctioning control module itself can cause issues with voltage regulation and trigger the B138A code. 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
B138A GMC indicates Control Module Voltage Reference Output Circuit.
Common causes
Common causes include Wiring Issues: Faulty or damaged wiring in the control module voltage reference output circuit can disrupt the voltage supply and trigger the B138A code, Connector Problems: Loose or corroded connectors can interfere with the proper transmission of voltage signals, leading to circuit malfunctions, Control Module Failure: A malfunctioning control module itself can cause issues with voltage regulation and trigger the B138A code.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 14, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code B138A GMC Description

The B138A GMC code indicates a problem with the Control Module Voltage Reference Output Circuit in the vehicle. The control module is responsible for regulating various functions within the vehicle, and the voltage reference output circuit plays a crucial role in ensuring that the correct voltage is supplied to different components. When this circuit malfunctions, it can lead to a variety of issues that may affect the vehicle's performance and overall functionality.

OBDII Code B138A GMC - Control Module Voltage Reference Output Circuit
B138A GMC Code - Control Module Voltage Reference Output Circuit

Common Causes of B138A GMC

  1. Wiring Issues: Faulty or damaged wiring in the control module voltage reference output circuit can disrupt the voltage supply and trigger the B138A code.
  2. Connector Problems: Loose or corroded connectors can interfere with the proper transmission of voltage signals, leading to circuit malfunctions.
  3. Control Module Failure: A malfunctioning control module itself can cause issues with voltage regulation and trigger the B138A code.
  4. Electrical Short Circuit: An electrical short circuit in the control module voltage reference output circuit can disrupt the flow of voltage and trigger the code.
  5. Battery Problems: Issues with the vehicle's battery, such as low voltage or poor connections, can also contribute to the B138A code.

Symptoms of B138A GMC

  1. Check Engine Light: The most common symptom associated with the B138A code is the illumination of the check engine light on the vehicle's dashboard.
  2. Erratic Electrical Behavior: The vehicle may experience erratic behavior in various electrical components, such as flickering lights, malfunctioning gauges, or non-responsive controls.
  3. Poor Performance: The vehicle may exhibit reduced performance, including sluggish acceleration, stalling, or difficulty starting.
  4. Electrical System Failure: In severe cases, the vehicle's electrical system may fail completely, leading to a loss of power to critical components.

How to Fix B138A GMC

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific trouble code and perform a thorough inspection of the control module voltage reference output circuit to identify the root cause of the problem.
  2. Check Wiring and Connectors: Inspect the wiring and connectors in the circuit for any signs of damage, corrosion, or loose connections. Repair or replace any faulty components as needed.
  3. Test Control Module: Test the control module to determine if it is functioning correctly. If the module is faulty, replace it with a new one.
  4. Clear Codes: Once the repairs have been completed, clear the trouble codes from the vehicle's memory using a diagnostic scanner to reset the check engine light.
  5. Test Drive: Take the vehicle for a test drive to ensure that the issue has been resolved and that the control module voltage reference output circuit is functioning properly.

Cost to Fix B138A GMC

The typical repair costs for addressing the B138A GMC code can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts for this repair can range from $100 to $500, while labor costs can range from $100 to $300. Overall, the total repair cost for this issue may fall between $200 and $800, but it's important to note that these estimates are approximate and can vary based on factors such as the vehicle make and model, the location of the repair shop, and the specific diagnosis time and labor rates. It's recommended to consult with a qualified mechanic or auto repair shop to obtain a more accurate cost estimate for addressing the B138A code.

What does this mean?

Tech Notes for B138A GMC

DTC B138A 03: Control Module Voltage Reference Output Circuit Low Voltage

DTC B138A 07: Control Module Voltage Reference Output Circuit High Voltage

Need more information about the B138A GMC code?

Need more information on how to fix the B138A GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B138A 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 B138A GMC Code

1. What are the common symptoms of OBDII code B138A GMC?

The common symptoms of OBDII code B138A GMC include issues with the vehicle's electrical system, such as dimming or flickering lights, erratic instrument cluster behavior, and difficulty starting the engine.

2. What causes the OBDII code B138A GMC to trigger?

The OBDII code B138A GMC is typically triggered when there is a malfunction in the control module voltage reference output circuit, which may be due to a faulty control module, wiring issues, or a failed voltage regulator.

3. How can I diagnose the OBDII code B138A GMC?

Diagnosing the OBDII code B138A GMC involves using a diagnostic scanner to retrieve the trouble codes, conducting a visual inspection of the wiring and connectors, testing the control module voltage output, and checking for any related technical service bulletins from the manufacturer.

4. Can I still drive my vehicle with the OBDII code B138A GMC?

It is not recommended to drive your vehicle with the OBDII code B138A GMC present, as it indicates a potential issue with the control module voltage reference output circuit that could lead to further electrical problems or engine issues.

5. How can I repair the OBDII code B138A GMC?

To repair the OBDII code B138A GMC, you may need to replace the faulty control module, repair any damaged wiring or connectors, or address any issues with the voltage regulator. It is recommended to consult a professional mechanic for an accurate diagnosis and repair.

6. Is the OBDII code B138A GMC a serious issue?

The OBDII code B138A GMC should be addressed promptly to prevent further damage to the vehicle's electrical system or control modules. Ignoring the code could lead to more severe problems and potential safety hazards.

7. Can a DIY enthusiast fix the OBDII code B138A GMC?

While some DIY enthusiasts may have the skills to diagnose and repair the OBDII code B138A GMC, it is recommended to seek professional help to ensure the issue is properly diagnosed and fixed, especially when dealing with complex control module circuits.

8. Are there any common mistakes to avoid when dealing with the OBDII code B138A GMC?

Common mistakes to avoid when dealing with the OBDII code B138A GMC include ignoring the code, misdiagnosing the issue as a simple wiring problem, or attempting repairs without the proper tools or knowledge.

9. How much does it cost to repair the OBDII code B138A GMC?

The cost of repairing the OBDII code B138A GMC can vary depending on the extent of the issue, the parts needed for the repair, and the labor costs. It is recommended to obtain quotes from different mechanics or repair shops for an accurate estimate.

10. Can the OBDII code B138A GMC be prevented?

While some causes of the OBDII code B138A GMC may be unavoidable, regular maintenance of the vehicle's electrical system, checking for any wiring issues, and addressing any warning signs promptly can help prevent the code from triggering.

Discuss the causes and fixes for B138A GMC OBDII Code

Submit a New Comment

Code B138A GMC comments

No comments found for this page.