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Engine-Codes – GMC – U1549 GMC

U1549 GMC Code - Body Control Module Lost Communication With Rear Wiper Motor On LIN Bus

Quick Answer

The U1549 GMC diagnostic trouble code indicates that the Body Control Module (BCM) has lost communication with the rear wiper motor on the Local Interconnect Network (LIN) bus. Common causes include Faulty rear wiper motor, Loose or corroded electrical connections between BCM and rear wiper motor, Defective BCM. 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
U1549 GMC indicates Body Control Module Lost Communication With Rear Wiper Motor On LIN Bus.
Common causes
Common causes include Faulty rear wiper motor, Loose or corroded electrical connections between BCM and rear wiper motor, Defective BCM.
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 15, 2024
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Code U1549 GMC Description

The U1549 GMC diagnostic trouble code indicates that the Body Control Module (BCM) has lost communication with the rear wiper motor on the Local Interconnect Network (LIN) bus. The LIN bus is a communication network used in modern vehicles to allow various control modules to communicate with each other. In this case, the BCM, which is responsible for controlling various body functions such as lighting, wipers, and door locks, is unable to communicate with the rear wiper motor.

OBDII Code U1549 GMC - Body Control Module Lost Communication With Rear Wiper Motor On LIN Bus
U1549 GMC Code - Body Control Module Lost Communication With Rear Wiper Motor On LIN Bus

Common Causes of U1549 GMC

  1. Faulty rear wiper motor
  2. Loose or corroded electrical connections between BCM and rear wiper motor
  3. Defective BCM
  4. Wiring harness issues
  5. Software glitches in the BCM

Symptoms of U1549 GMC

  1. Rear wiper not working
  2. Rear wiper working intermittently
  3. Dashboard warning light related to rear wiper system
  4. Inability to control rear wiper settings from the switch

How to Fix U1549 GMC

  1. Begin by conducting a visual inspection of the rear wiper motor and its electrical connections to check for any visible damage, corrosion, or loose connections.
  2. Use a diagnostic scan tool to communicate with the BCM and retrieve any stored fault codes related to the communication loss with the rear wiper motor.
  3. Test the rear wiper motor for proper functionality by applying power directly to it to see if it operates.
  4. If the rear wiper motor is functioning correctly, focus on checking the wiring harness for any breaks, shorts, or damage.
  5. If no visible issues are found with the wiring or motor, consider reprogramming or replacing the BCM to address any software-related issues.

Cost to Fix U1549 GMC

The typical repair costs for addressing the U1549 GMC code can vary depending on the specific cause of the issue. In general, replacing a faulty rear wiper motor can cost between $150 to $300, while repairing or replacing a BCM can range from $300 to $800. Labor costs can add an additional $80 to $150 per hour, and the total repair bill can vary based on the location, vehicle make and model, and the specific diagnosis time required. It is advisable to consult with a qualified mechanic or auto repair shop to obtain an accurate estimate for addressing this issue.

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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 U1549 GMC Code

1. What are the common symptoms of OBDII code U1549 in a GMC vehicle?

- Common symptoms include the rear wiper not functioning, erratic rear wiper operation, warning lights on the dashboard, and issues with other body control functions.

2. What does the OBDII code U1549 GMC mean?

- The code indicates that the Body Control Module has lost communication with the rear wiper motor on the LIN Bus network.

3. What are the possible causes of the Body Control Module losing communication with the rear wiper motor?

- Potential causes include a faulty rear wiper motor, damaged wiring or connectors, a malfunctioning Body Control Module, or issues with the LIN Bus network.

4. How can I diagnose the cause of the communication loss between the Body Control Module and the rear wiper motor?

- Diagnosing the issue may involve conducting a visual inspection of wiring and connectors, testing the rear wiper motor for functionality, and using a scan tool to check for communication errors.

5. Is it safe to continue driving with OBDII code U1549 present in my GMC vehicle?

- It is generally safe to drive with this code, but it is recommended to address the issue promptly to ensure proper functioning of the rear wiper and other related systems.

6. Can I repair OBDII code U1549 GMC on my own, or should I seek professional help?

- Depending on your experience and access to tools, you may be able to address this issue on your own by checking wiring connections and components. However, seeking professional help is recommended for more complex diagnostics and repairs.

7. Are there any quick tips for troubleshooting OBDII code U1549 in a GMC vehicle?

- Quick tips include checking fuses related to the rear wiper system, inspecting wiring for visible damage, and resetting the Body Control Module by disconnecting the battery for a few minutes.

8. Will resetting the Body Control Module clear the U1549 code?

- Resetting the Body Control Module may clear the code temporarily, but if the underlying issue causing the communication loss is not resolved, the code is likely to reappear.

9. How much does it typically cost to repair OBDII code U1549 in a GMC vehicle?

- Repair costs can vary depending on the specific cause of the issue, but they may range from a few hundred dollars for simple fixes like wiring repairs to over a thousand dollars for more complex repairs involving module replacement.

10. Can OBDII code U1549 in a GMC be prevented in the future?

- Regular maintenance checks, ensuring proper wiring connections, and addressing any issues promptly can help prevent the recurrence of the communication loss between the Body Control Module and the rear wiper motor.

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