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

Quick Answer

The U1549 code for Cadillac indicates that there is a communication problem between the Body Control Module (BCM) and the Rear Wiper Motor on the Local Interconnect Network (LIN) bus. Common causes include Faulty rear wiper motor, Corroded or damaged wiring harness between BCM and rear wiper motor, Failed Body Control Module. 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 Cadillac indicates Body Control Module Lost Communication With Rear Wiper Motor On LIN Bus.
Common causes
Common causes include Faulty rear wiper motor, Corroded or damaged wiring harness between BCM and rear wiper motor, Failed Body Control Module.
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 09, 2024
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Code U1549 Cadillac Description

The U1549 code for Cadillac indicates that there is a communication problem between the Body Control Module (BCM) and 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 modules to communicate with each other. When the BCM loses communication with the rear wiper motor, it can lead to issues with controlling the rear wiper function, affecting visibility during inclement weather conditions.

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

Common Causes of U1549 Cadillac

  1. Faulty rear wiper motor.
  2. Corroded or damaged wiring harness between BCM and rear wiper motor.
  3. Failed Body Control Module.
  4. Communication error on the LIN bus network.
  5. Water ingress causing electrical issues.

Symptoms of U1549 Cadillac

  1. Rear wiper not responding to control inputs.
  2. Intermittent operation of the rear wiper.
  3. Rear wiper operating at incorrect speeds.
  4. Warning light on the dashboard indicating a communication fault.

How to Fix U1549 Cadillac

  1. Begin by conducting a thorough visual inspection of the wiring harness for any signs of damage or corrosion. Repair or replace any damaged wiring.
  2. Test the rear wiper motor for functionality and replace if necessary.
  3. Use a diagnostic scan tool to check for communication errors between the BCM and rear wiper motor. Reset any fault codes and retest the system.
  4. If the issue persists, consider replacing the Body Control Module.
  5. Finally, perform a complete system check to ensure that the rear wiper is functioning correctly and that there are no other related issues.

Cost to Fix U1549 Cadillac

The cost of repairing the U1549 code on a Cadillac can vary depending on the specific cause of the issue. Generally, the cost of replacing a rear wiper motor can range from $150 to $300, while a new Body Control Module can cost anywhere from $200 to $500. Labor costs for diagnosis and repair can add an additional $100 to $300, depending on the shop's hourly rates. Overall, the total repair cost for this issue could range from $250 to $800 or more, depending on the extent of the problem and the parts needed. It is advisable to consult a professional mechanic for an accurate estimate based on the specific vehicle and location.

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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 Cadillac Code

1. What are the common symptoms of OBDII code U1549 in a Cadillac related to the Body Control Module losing communication with the rear wiper motor?

The common symptoms include the rear wiper not functioning, the rear wiper operating erratically, and dashboard warning lights related to the wiper system.

2. What are the possible causes of the Body Control Module losing communication with the rear wiper motor on the LIN bus in a Cadillac?

Possible causes can include a faulty rear wiper motor, damaged wiring or connectors in the LIN bus circuit, a malfunctioning Body Control Module, or software issues.

3. How can I diagnose the issue causing OBDII code U1549 in a Cadillac?

Diagnosis involves conducting a thorough inspection of the rear wiper motor, checking the wiring and connectors for any damage, testing the LIN bus communication, and using a scan tool to retrieve specific fault codes.

4. Can I still drive my Cadillac with OBDII code U1549 present?

While it may be possible to drive the vehicle, it is not recommended as the rear wiper plays a crucial role in visibility during adverse weather conditions. It is best to address the issue promptly.

5. Are there any DIY repair tips for resolving OBDII code U1549 in a Cadillac?

DIY repair tips include checking and securing the wiring connections, inspecting the rear wiper motor for any visible damage, and resetting the Body Control Module by disconnecting the battery for a few minutes.

6. Do I need specialized tools to fix the issue related to the Body Control Module losing communication with the rear wiper motor on the LIN bus in a Cadillac?

While basic tools may be sufficient for inspecting wiring and connectors, diagnosing and repairing LIN bus communication issues may require specialized diagnostic tools and equipment.

7. How much does it typically cost to repair OBDII code U1549 in a Cadillac at a dealership or repair shop?

The cost of repair can vary depending on the specific cause of the issue. It is advisable to consult with a dealership or repair shop for a detailed diagnosis and cost estimate.

8. Is OBDII code U1549 in a Cadillac a common issue, or is it specific to certain models or years?

This code can occur in various Cadillac models with rear wiper systems and LIN bus communication. However, the frequency of occurrence may vary based on the specific vehicle and its age.

9. Can ignoring OBDII code U1549 lead to other problems in my Cadillac?

Continued operation with this issue unresolved may lead to further electrical malfunctions, potential damage to the rear wiper system components, and compromising the safety of the vehicle in certain driving conditions.

10. After repairing OBDII code U1549 in a Cadillac, should I reset the fault codes and clear the Check Engine light?

Once the issue is fixed, it is recommended to reset the fault codes using a scan tool and clear the Check Engine light to ensure the system registers the repair and monitors the vehicle's performance accurately.

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