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

Quick Answer

The U1555 diagnostic trouble code for Cadillac vehicles indicates that the Body Control Module (BCM) has lost communication with the Left Rear Seat Heating/Venting/Cooling Switch on the Local Interconnect Network (LIN) bus. Common causes include Faulty Left Rear Seat Heating/Venting/Cooling Switch, Wiring or connection issues between the switch and the BCM, BCM malfunction. 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 Cadillac indicates Body Control Module Lost Communication With Left Rear Seat Heating/Venting/Cooling Switch On LIN Bus.
Common causes
Common causes include Faulty Left Rear Seat Heating/Venting/Cooling Switch, Wiring or connection issues between the switch and the BCM, BCM malfunction.
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 16, 2024
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Code U1555 Cadillac Description

The U1555 diagnostic trouble code for Cadillac vehicles indicates that the Body Control Module (BCM) has lost communication with the Left Rear Seat Heating/Venting/Cooling Switch on the Local Interconnect Network (LIN) bus. The LIN bus is a communication network used in modern vehicles to allow various components to communicate with each other. In this case, the BCM is unable to establish communication with the switch responsible for controlling the left rear seat's heating, venting, and cooling functions.

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

Common Causes of U1555 Cadillac

  1. Faulty Left Rear Seat Heating/Venting/Cooling Switch.
  2. Wiring or connection issues between the switch and the BCM.
  3. BCM malfunction.
  4. Software glitches in the BCM programming.
  5. Electrical interference affecting communication on the LIN bus.

Symptoms of U1555 Cadillac

  1. Inability to control the heating, venting, or cooling functions of the left rear seat.
  2. Malfunctioning climate control settings specifically for the left rear seat.
  3. Warning lights related to the climate control system appearing on the dashboard.
  4. Erratic behavior of other systems that rely on data from the left rear seat switch.

How to Fix U1555 Cadillac

  1. Begin by conducting a thorough inspection of the Left Rear Seat Heating/Venting/Cooling Switch and its wiring connections. Replace the switch if it is found to be faulty.
  2. Check the wiring harness between the switch and the BCM for any damage or loose connections. Repair or replace any damaged wiring.
  3. Perform a diagnostic scan to assess the BCM's functionality and identify any software issues. Update or reprogram the BCM as necessary.
  4. Clear the U1555 trouble code from the vehicle's memory using a diagnostic scanner.
  5. Test the left rear seat's climate control functions to ensure proper communication and operation.

Cost to Fix U1555 Cadillac

The typical repair costs for addressing the U1555 code on a Cadillac vehicle can range from $150 to $400, depending on the specific cause of the issue and the labor rates at the auto repair shop. Parts such as a new switch or wiring harness may incur additional costs. It is advisable to consult with a professional mechanic for an accurate estimate based on the vehicle's make and model, as well as the local labor rates.

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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 U1555 Cadillac Code

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

The common symptoms include malfunctioning left rear seat heating/cooling system, inoperative seat ventilation, and issues with the seat control switch.

2. What are the potential causes of OBDII code U1555 in a Cadillac?

The code U1555 is typically triggered by a faulty left rear seat heating/cooling switch, damaged wiring or connectors in the LIN bus communication system, or a malfunctioning Body Control Module.

3. How can I diagnose the issue related to OBDII code U1555 in a Cadillac?

Diagnosing the issue involves checking the wiring and connectors for any damage, testing the left rear seat heating/cooling switch for functionality, and using a diagnostic scan tool to communicate with the Body Control Module.

4. Can I repair OBDII code U1555 in a Cadillac by myself?

If you have experience working on automotive electrical systems, you may be able to repair the issue yourself by identifying and fixing any damaged wiring or connectors, replacing the faulty switch, or reprogramming the Body Control Module if necessary.

5. Is it safe to drive my Cadillac with OBDII code U1555 present?

While the vehicle may still be operational with this code, it is recommended to address the issue promptly to avoid any potential safety hazards or further damage to the electrical system.

6. Are there any temporary fixes for OBDII code U1555 in a Cadillac?

Temporary fixes such as resetting the code using a diagnostic scanner or disconnecting and reconnecting the battery may sometimes clear the code temporarily, but it is crucial to address the root cause of the problem for a permanent solution.

7. Can weather conditions affect the occurrence of OBDII code U1555 in a Cadillac?

Extreme temperatures or moisture can sometimes exacerbate issues with the LIN bus communication system, potentially leading to the Body Control Module losing communication with the left rear seat heating/cooling switch.

8. How much does it typically cost to repair OBDII code U1555 in a Cadillac?

The cost of repair can vary depending on the exact cause of the issue, but it may involve expenses for parts replacement, wiring repairs, or diagnostic services from a qualified mechanic or dealership.

9. Will OBDII code U1555 cause any other electrical problems in my Cadillac?

While the code specifically relates to the communication issue with the left rear seat heating/cooling switch, it is essential to address it promptly to prevent any potential cascading effects on other electrical components in the vehicle.

10. How long does it usually take to repair OBDII code U1555 in a Cadillac?

The repair time can vary based on the complexity of the issue and the availability of parts, but it is advisable to consult with a professional technician to get an accurate estimate of the repair duration.

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