AutoCodes – Generic – C1115:5A

C1115:5A Code - Manual Trailer Brake Apply Request Switch Signal Plausibility Failure

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: C1115:5A indicates Manual Trailer Brake Apply Request Switch Signal Plausibility Failure.
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 309

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
Tech Notes
Cost to Diagnose
Comments
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Code C1115:5A 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. The Diagnostic Trouble Code (DTC) will be set when the Chassis Control Module-Auxiliary detects the manual apply switch is continuously applied for 30 seconds after ignition is cycled to ON.

OBDII Code C1115:5A - Manual Trailer Brake Apply Request Switch Signal Plausibility Failure - AutoCodes.com — C1115:5A Code - Manual Trailer Brake Apply Request Switch Signal Plausibility Failure

What does this mean?

What are the Possible Causes of the DTC C1115:5A?

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 C1115:5A?

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

C1115:08 Manual Trailer Brake Apply Request Switch Signal Invalid
C1115:5A Manual Trailer Brake Apply Request Switch Signal Plausibility Failure

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C1115:5A 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.

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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.