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Engine-Codes – Generic – U1555

U1555 Code - Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus

Quick Answer

The diagnostic trouble code U1555 indicates that the Body Control Module (BCM) has lost communication with the left rear seat heating/venting/cooling switch on the LIN bus. Common causes include Faulty wiring or connectors between the BCM and the left rear seat switch, Malfunctioning left rear seat switch, Software communication error within the vehicle's network. 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
U1555 indicates Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus.
Common causes
Common causes include Faulty wiring or connectors between the BCM and the left rear seat switch, Malfunctioning left rear seat switch, Software communication error within the vehicle's network.
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 08, 2024
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Code U1555 Description

The diagnostic trouble code U1555 indicates that the Body Control Module (BCM) has lost communication with the left rear seat heating/venting/cooling switch on the LIN bus. The LIN bus is a communication network in modern vehicles that allows various control modules to communicate with each other. In this case, the BCM, which is responsible for controlling various body functions such as lighting, door locks, and climate control, is unable to communicate with the switch that controls the heating, venting, and cooling functions of the left rear seat.

OBDII Code U1555 - Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus
U1555 Code - Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus

Common Causes of U1555

  1. Faulty wiring or connectors between the BCM and the left rear seat switch.
  2. Malfunctioning left rear seat switch.
  3. Software communication error within the vehicle's network.
  4. BCM failure.
  5. Electrical interference or damage to the LIN bus communication network.

Symptoms of U1555

  1. Inoperative heating, venting, or cooling functions in the left rear seat.
  2. Error message or warning light related to the body control module on the instrument cluster.
  3. Inconsistent operation of other body functions controlled by the BCM.
  4. Electrical issues such as flickering lights or malfunctioning door locks.

How to Fix U1555

  1. Begin by conducting a thorough visual inspection of the wiring and connectors between the BCM and the left rear seat switch. Look for any signs of damage, corrosion, or loose connections, and repair or replace as necessary.
  2. Test the left rear seat switch for functionality using a multimeter or diagnostic tool. Replace the switch if it is found to be faulty.
  3. Use a diagnostic scanner to check for any error codes related to the BCM and clear them if necessary. Resetting the system may help reestablish communication.
  4. If the issue persists, consider reprogramming or updating the software of the BCM to address any communication errors within the vehicle's network.
  5. If all else fails, it may be necessary to replace the BCM or seek professional assistance to further diagnose and repair the issue.

Cost to Fix U1555

The cost of repairing a U1555 diagnostic trouble code can vary depending on the specific cause of the issue and the labor rates in your area. Typically, replacing a faulty left rear seat switch can cost between $50 to $150, while repairing or reprogramming the BCM can range from $200 to $500. Additional costs for diagnostic testing, parts, and labor may apply. It's recommended to consult with a reputable auto repair shop or dealership for a more accurate estimate based on your vehicle's make and model.

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Code U1555 Information for Specific Makes

  • U1555 Buick — Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus
  • U1555 Cadillac — Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus
  • U1555 Chevrolet — Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus
  • U1555 GMC — Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus
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 U1555 Code

1. What are the common symptoms of OBDII code U1555 related to the Body Control Module losing communication with the left rear seat heating/cooling switch?

- Common symptoms include inoperative left rear seat heating/cooling functionality, malfunctioning seat vents, or issues with seat cooling features.

2. What are the possible causes of OBDII code U1555 indicating communication loss with the left rear seat heating/cooling switch?

- Potential causes include a faulty left rear seat heating/cooling switch, damaged wiring or connectors in the LIN bus network, or a malfunctioning Body Control Module.

3. How can I diagnose the issue causing OBDII code U1555 to determine if it's related to the left rear seat heating/cooling switch communication loss?

- Use a diagnostic scan tool to check for specific trouble codes, inspect the wiring and connectors associated with the left rear seat switch, and perform a LIN bus communication test.

4. Is it safe to continue driving with OBDII code U1555 triggered by the Body Control Module losing communication with the left rear seat heating/cooling switch?

- It is generally safe to drive, but it's recommended to address the issue promptly to ensure the proper functioning of the left rear seat heating/cooling system.

5. Are there any DIY repair tips for resolving OBDII code U1555 related to the communication loss with the left rear seat heating/cooling switch?

- DIY repair tips may include checking and repairing any damaged wiring, ensuring connectors are securely attached, and resetting the Body Control Module to see if communication is restored.

6. Can a professional mechanic help with diagnosing and repairing OBDII code U1555 associated with the left rear seat heating/cooling switch communication issue?

- Yes, a professional mechanic with experience in automotive diagnostics can accurately diagnose the problem, perform necessary repairs, and reset the system to clear the code.

7. How much does it typically cost to repair OBDII code U1555 related to the Body Control Module losing communication with the left rear seat heating/cooling switch?

- Repair costs can vary depending on the exact cause of the issue, but it may involve replacing the left rear seat switch, repairing wiring, or reprogramming the Body Control Module.

8. Will resetting the OBDII code U1555 resolve the communication problem with the left rear seat heating/cooling switch?

- Resetting the code may temporarily clear the fault, but it's crucial to address the underlying issue causing the communication loss to prevent the code from reoccurring.

9. Are there any recalls or technical service bulletins related to OBDII code U1555 and the Body Control Module's communication with the left rear seat heating/cooling switch?

- Check with the vehicle manufacturer or authorized dealerships to inquire about any recalls or technical service bulletins addressing this specific issue for your vehicle model.

10. How can I prevent OBDII code U1555 from occurring again after repairing the communication problem with the left rear seat heating/cooling switch?

- Regularly inspect and maintain the wiring and connectors associated with the left rear seat switch, follow recommended maintenance schedules, and address any related issues promptly to prevent code recurrence.

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