AutoCodes – GMC – C1118 2015 GMC Sierra

C1118 2015 GMC Sierra Code - Trailer Brake Control Sensitivity Switch Circuit Malfunction

Quick Answer

The trailer brake control system has a control panel with the trailer gain and manual apply switches. Common causes include Faulty Trailer Brake Control Switch, Trailer Brake Control Switch harness is open or shorted, Trailer Brake Control Switch 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: C1118 2015 GMC Sierra indicates Trailer Brake Control Sensitivity Switch Circuit Malfunction.
Common causes: Common causes include Faulty Trailer Brake Control Switch, Trailer Brake Control Switch harness is open or shorted, Trailer Brake Control Switch 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.

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Code Popularity 171

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 Jul 18, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C1118 2015 GMC Sierra Description

The trailer brake control system has a control panel with the trailer gain and manual apply switches. The switches are located on the instrument panel to the left of the steering column. The control panel and switches allow you to adjust the amount of output, referred to as trailer gain, available to the electric trailer brakes and allow you to manually apply the trailer brakes. The trailer brake control panel and switches are used along with the trailer brake display page on the driver information center to adjust and display power output to the trailer brakes.

OBDII Code C1118 2015 GMC Sierra - Trailer Brake Control Sensitivity Switch Circuit Malfunction - AutoCodes.com — C1118 2015 GMC Sierra Code - Trailer Brake Control Sensitivity Switch Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC C1118 2015 GMC Sierra?

Faulty Trailer Brake Control Switch
Trailer Brake Control Switch harness is open or shorted
Trailer Brake Control Switch circuit poor electrical connection
Faulty Chassis Control Module-Auxiliary

How to Fix the DTC C1118 2015 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C1118 2015 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 C1118 2015 GMC Sierra code?

Need more information on how to fix the C1118 2015 GMC Sierra code? Get Access to Factory Service Manuals

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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 C1118 2015 GMC Sierra Code

1. What does the OBDII code C1118 mean on a 2015 GMC Sierra?

The C1118 code indicates a "Trailer Brake Control Sensitivity Switch Circuit Malfunction," meaning there is an issue with the electrical circuit controlling the trailer brake sensitivity.

2. What are the common symptoms of the C1118 code on a 2015 GMC Sierra?

Symptoms may include the trailer brake system not working properly, a warning light on the dashboard, or difficulty adjusting the trailer brake sensitivity.

3. What causes the C1118 code to trigger on a 2015 GMC Sierra?

Common causes include a faulty trailer brake sensitivity switch, damaged wiring or connectors in the circuit, or a malfunctioning trailer brake control module.

4. Can I still drive my 2015 GMC Sierra with the C1118 code active?

Yes, you can drive the truck, but the trailer brake system may not function properly, which could compromise safety when towing.

5. How do I diagnose the C1118 code on my 2015 GMC Sierra?

Diagnose the issue by inspecting the trailer brake sensitivity switch, checking the wiring and connectors for damage, and testing the trailer brake control module with a scan tool.

6. What tools do I need to fix the C1118 code on a 2015 GMC Sierra?

You may need a multimeter, an OBDII scan tool, and basic hand tools to check and repair the switch, wiring, or control module.

7. How can I fix the C1118 code on my 2015 GMC Sierra?

Repair steps include replacing the faulty trailer brake sensitivity switch, repairing damaged wiring or connectors, or replacing the trailer brake control module if necessary.

8. How much does it cost to fix a C1118 code on a 2015 GMC Sierra?

Repair costs can vary but typically range from $100 to $300 for parts and labor, depending on whether the switch, wiring, or module needs replacing.

9. Can a faulty trailer brake control module cause the C1118 code?

Yes, a malfunctioning trailer brake control module can cause the C1118 code by failing to properly process trailer brake sensitivity inputs.

10. Do I need to reprogram the trailer brake control module after fixing the C1118 code?

In some cases, the module may need reprogramming or recalibration after replacement or repair. Consult the vehicle's service manual or a professional technician.