AutoCodes – GMC – C1116 2018 GMC Sierra

C1116 2018 GMC Sierra Code - Manual Trailer Brake Apply Request Signal 1 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: C1116 2018 GMC Sierra indicates Manual Trailer Brake Apply Request Signal 1 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 319

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 C1116 2018 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 C1116 2018 GMC Sierra - Manual Trailer Brake Apply Request Signal 1 Malfunction - AutoCodes.com — C1116 2018 GMC Sierra Code - Manual Trailer Brake Apply Request Signal 1 Malfunction

What does this mean?

What are the Possible Causes of the DTC C1116 2018 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 C1116 2018 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 C1116 2018 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 C1116 2018 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 C1116 2018 GMC Sierra Code

What does the OBDII code C1116 mean on a 2018 GMC Sierra?

Code C1116 refers to a malfunction in the Manual Trailer Brake Apply Request Signal 1, indicating an issue with the trailer brake system's electrical signal.

What are common symptoms of code C1116 in a 2018 GMC Sierra?

Symptoms may include the trailer brakes not functioning properly, a "Service Trailer Brake System" warning on the dashboard, or difficulty manually applying trailer brakes.

What causes code C1116 on a 2018 GMC Sierra?

Common causes include a faulty trailer brake control module, damaged wiring or connectors, or issues with the manual brake apply switch.

Can I still tow a trailer if code C1116 is present on my 2018 GMC Sierra?

It is not recommended to tow a trailer until the issue is resolved, as the trailer brakes may not function correctly, posing a safety risk.

How do I diagnose code C1116 on a 2018 GMC Sierra?

Start by inspecting the wiring and connectors for the trailer brake system, checking for damage or corrosion, and testing the manual brake apply switch with a multimeter.

Is code C1116 a serious issue for my 2018 GMC Sierra?

Yes, it can be serious as it affects the trailer brake system, compromising towing safety and control. Prompt diagnosis and repair are recommended.

How can I fix code C1116 on my 2018 GMC Sierra?

Repair may involve replacing the manual brake apply switch, repairing damaged wiring or connectors, or replacing the trailer brake control module.

Can a faulty trailer brake apply switch trigger code C1116?

Yes, a malfunctioning manual trailer brake apply switch can cause this code by failing to send the proper signal to the brake control module.

Does code C1116 require professional repair?

While some experienced DIYers may be able to resolve the issue, professional diagnosis is often recommended for trailer brake system problems to ensure safe operation.

Will clearing the code C1116 solve the problem on a 2018 GMC Sierra?

Clearing the code without addressing the underlying issue will not fix the problem, and the code is likely to return until proper repairs are made.