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Engine-Codes – GMC – C111B 2015 GMC Sierra

C111B 2015 GMC Sierra Code - Trailer Brake Power Control Module System Voltage

Quick Answer

The C111B diagnostic trouble code (DTC) for a 2015 GMC Sierra relates to the Trailer Brake Power Control Module System Voltage. Common causes include Faulty trailer brake power control module, Wiring issues or shorts in the electrical system, Malfunctioning battery affecting voltage supply. 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
C111B 2015 GMC Sierra indicates Trailer Brake Power Control Module System Voltage.
Common causes
Common causes include Faulty trailer brake power control module, Wiring issues or shorts in the electrical system, Malfunctioning battery affecting voltage supply.
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 10, 2024
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Code C111B 2015 GMC Sierra Description

The C111B diagnostic trouble code (DTC) for a 2015 GMC Sierra relates to the Trailer Brake Power Control Module System Voltage. This code indicates that there is an issue with the voltage supplied to the trailer brake power control module. The trailer brake power control module is responsible for managing the power supply to the trailer brakes, ensuring that they operate correctly. When the system voltage is not within the expected range, it can lead to various issues with the trailer's braking system, affecting the vehicle's towing capabilities.

OBDII Code C111B 2015 GMC Sierra - Trailer Brake Power Control Module System Voltage
C111B 2015 GMC Sierra Code - Trailer Brake Power Control Module System Voltage

Common Causes of C111B 2015 GMC Sierra

  1. Faulty trailer brake power control module
  2. Wiring issues or shorts in the electrical system
  3. Malfunctioning battery affecting voltage supply
  4. Faulty alternator not charging the battery properly
  5. Voltage regulator malfunction affecting system voltage

Symptoms of C111B 2015 GMC Sierra

  1. Trailer brakes not engaging properly
  2. ABS warning light illuminated on the dashboard
  3. Inconsistent brake performance while towing
  4. Voltage fluctuations in the electrical system
  5. Trailer brake system error messages on the vehicle's display

How to Fix C111B 2015 GMC Sierra

  1. Begin by conducting a thorough inspection of the trailer brake power control module and associated wiring to identify any visible damage or loose connections.
  2. Test the battery and alternator to ensure they are functioning correctly and providing the appropriate voltage to the trailer brake system.
  3. Check the voltage regulator for any malfunctions and replace if necessary.
  4. If the trailer brake power control module is found to be faulty, replace it with a new unit following manufacturer guidelines.
  5. Clear the DTC using a diagnostic tool and test the trailer brake system to ensure proper functionality before towing.

Cost to Fix C111B 2015 GMC Sierra

The typical repair costs for addressing the C111B code on a 2015 GMC Sierra can vary depending on the specific cause of the issue. In general, replacing a faulty trailer brake power control module can cost between $200 and $500, including parts and labor. However, additional costs may be incurred if other components such as the battery, alternator, or wiring need to be replaced or repaired. It is advisable to consult with a professional mechanic for a more accurate cost estimate based on the specific diagnosis of the vehicle. Keep in mind that labor rates at auto repair shops can vary, so it's essential to consider factors such as location and shop rates when budgeting for repairs.

What does this mean?

Tech Notes for C111B 2015 GMC Sierra

C111B:03 Trailer Brake Power Control Module System Voltage Below Threshold

C111B:07 Trailer Brake Power Control Module System Voltage Above Threshold

C111B:5A Trailer Brake Power Control Module System Voltage Plausibility Failure

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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 C111B 2015 GMC Sierra Code

1. What does OBDII code C111B mean on a 2015 GMC Sierra?

C111B indicates an issue with the Trailer Brake Power Control Module System Voltage, typically signaling a problem with the electrical supply to the module.

2. What are the common symptoms of code C111B on a 2015 GMC Sierra?

Symptoms may include a "Service Trailer Brake System" message on the dashboard, non-functional trailer brakes, or inconsistent trailer braking performance.

3. What causes the C111B code to activate?

Common causes include a weak or failing battery, corroded or loose electrical connections, damaged wiring, or a faulty Trailer Brake Power Control Module.

4. Can a blown fuse cause the C111B code on a GMC Sierra?

Yes, a blown fuse in the trailer brake system circuit can interrupt power to the control module and trigger the C111B code.

5. How can I troubleshoot the C111B code on my 2015 GMC Sierra?

Start by checking the battery voltage, inspecting fuses related to the trailer brake system, and examining wiring and connectors for damage or corrosion.

6. Does the trailer brake control module need to be replaced to fix code C111B?

Not always. The issue could be resolved by repairing wiring, replacing a fuse, or addressing a low battery. Replace the module only if it is confirmed to be faulty.

7. Can towing a damaged trailer trigger the C111B code?

Yes, if the trailer’s wiring has shorts or faults, it can cause voltage issues in the truck's trailer brake system and trigger the code.

8. How much does it cost to fix the C111B code on a 2015 GMC Sierra?

Repair costs vary depending on the issue but typically range from $50 for minor wiring repairs to $500 or more for module replacement.

9. Can I still tow a trailer with the C111B code active?

It is not recommended, as the trailer brakes may not function properly, posing a safety risk.

10. Will clearing the C111B code fix the underlying issue?

No, clearing the code will not resolve the problem. The issue causing the voltage fault must be identified and fixed to prevent the code from returning.

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