AutoCodes – Generic – C1749

C1749 Code - Trailer Input Circuit Failure

Quick Answer

The Anti-Lock Brake System (ABS) Module monitors the Trailer Input Switch. Common causes include Faulty Trailer Input Switch, Trailer Input Switch harness is open or shorted, Trailer Input 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: C1749 indicates Trailer Input Circuit Failure.
Common causes: Common causes include Faulty Trailer Input Switch, Trailer Input Switch harness is open or shorted, Trailer Input 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 3,855

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 Nov 19, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C1749 Description

The Anti-Lock Brake System (ABS) Module monitors the Trailer Input Switch. The ABS Module sets the OBDII code when the Trailer Input Switch is not to factory specifications.

OBDII Code C1749 - Trailer Input Circuit Failure - AutoCodes.com — C1749 Code - Trailer Input Circuit Failure

What does this mean?

What are the Possible Causes of the DTC C1749?

Faulty Trailer Input Switch
Trailer Input Switch harness is open or shorted
Trailer Input Switch circuit poor electrical connection

How to Fix the DTC C1749?

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 C1749 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 C1749 code?

Need more information on how to fix the C1749 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C1749 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 C1749 Code

1. What are the common symptoms of OBDII code C1749 (Trailer Input Circuit Failure)?

- The common symptoms include the illumination of the Check Engine Light, issues with trailer brake operation, and possible loss of communication with the trailer.

2. What are the potential causes of OBDII code C1749?

- The code C1749 can be triggered by issues such as damaged wiring in the trailer input circuit, faulty trailer brake control module, or poor connections.

3. How can I diagnose the Trailer Input Circuit Failure related to code C1749?

- To diagnose the issue, you can start by checking the trailer wiring for any damages, inspecting the connections, and testing the trailer brake control module for proper functionality.

4. What are some repair tips for resolving OBDII code C1749?

- Repair tips may include repairing or replacing damaged wiring, ensuring secure connections, and replacing the trailer brake control module if necessary.

5. Can I drive my vehicle with OBDII code C1749 present?

- It is generally not recommended to drive with unresolved OBDII codes, including code C1749, as it can affect the proper functioning of the trailer brake system and pose safety risks.

6. How do I reset the OBDII code C1749 after making repairs?

- After making the necessary repairs, you can reset the code using an OBDII scanner or by disconnecting the vehicle's battery for a few minutes to clear the fault code.

7. Are there any precautions to take when working on the trailer input circuit for code C1749?

- When working on the trailer input circuit, it is important to disconnect the battery, follow proper safety procedures, and refer to the vehicle's service manual for guidance.

8. Can a DIY enthusiast fix OBDII code C1749 at home?

- Depending on the individual's skill level and access to tools, a DIY enthusiast may be able to diagnose and repair code C1749 related to the trailer input circuit failure.

9. How can I prevent OBDII code C1749 from recurring in the future?

- To prevent the recurrence of code C1749, it is essential to maintain the trailer wiring in good condition, perform regular inspections, and address any issues promptly.

10. Is it necessary to visit a mechanic for OBDII code C1749, or can I troubleshoot it myself?

- While some may be able to troubleshoot and repair code C1749 themselves, it is recommended to seek professional help if unsure about diagnosing or resolving the issue effectively.