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U1503 Chrysler Code - Implausible Message Data Length Received From FCM

Quick Answer

The U1503 code for Chrysler vehicles indicates that the Body Control Module (BCM) has received a message with an implausible data length from the Forward Control Module (FCM). Common causes include Faulty wiring or connectors between the BCM and FCM, Defective BCM or FCM, Software issues or programming errors in the modules. 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
U1503 Chrysler indicates Implausible Message Data Length Received From FCM.
Common causes
Common causes include Faulty wiring or connectors between the BCM and FCM, Defective BCM or FCM, Software issues or programming errors in the modules.
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 11, 2024
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Code U1503 Chrysler Description

The U1503 code for Chrysler vehicles indicates that the Body Control Module (BCM) has received a message with an implausible data length from the Forward Control Module (FCM). The FCM is responsible for controlling various functions related to safety and convenience, such as lighting, door locks, and security systems. When the BCM receives data from the FCM that does not match the expected length, it can lead to communication errors and malfunctions within the vehicle's electronic systems.

OBDII Code U1503 Chrysler - Implausible Message Data Length Received From FCM
U1503 Chrysler Code - Implausible Message Data Length Received From FCM

Common Causes of U1503 Chrysler

  1. Faulty wiring or connectors between the BCM and FCM
  2. Defective BCM or FCM
  3. Software issues or programming errors in the modules
  4. Water damage or corrosion in the module connectors
  5. Electrical interference or electromagnetic interference affecting communication

Symptoms of U1503 Chrysler

  1. Erratic behavior of lights (flashing, not working, staying on)
  2. Malfunctioning door locks (not locking/unlocking properly)
  3. Security system issues (false alarms, inability to arm/disarm)
  4. Vehicle not starting or intermittent starting issues
  5. Loss of communication with other modules in the vehicle

How to Fix U1503 Chrysler

  1. Diagnose the exact cause of the communication error using a diagnostic scanner to retrieve specific fault codes.
  2. Inspect the wiring and connectors between the BCM and FCM for any damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Check for any software updates or reprogramming required for the BCM and FCM to ensure compatibility and proper communication.
  4. Test the communication between the modules after repairs are made to confirm that the issue has been resolved.
  5. Clear the fault codes and perform a test drive to verify that the systems are functioning correctly.

Cost to Fix U1503 Chrysler

The typical repair costs for addressing the U1503 code can vary depending on the exact cause of the issue and the labor rates at the auto repair shop. In general, repairing communication errors between modules can range from $200 to $500, including parts and labor. However, it's essential to consider that diagnostic time and labor rates can vary significantly based on the location, vehicle make and model, and the expertise of the technician. It's advisable to consult with a trusted auto repair shop for a more accurate estimate based on the specific circumstances.

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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 U1503 Chrysler Code

1. What are the common symptoms of OBDII code U1503 in a Chrysler vehicle?

- Common symptoms include issues with the vehicle's electronic control systems, such as dashboard warning lights, erratic behavior of components, and potential drivability issues.

2. What does the OBDII code U1503 Chrysler mean?

- The code U1503 indicates an implausible message data length received from the FCM (Front Control Module) in Chrysler vehicles.

3. What are the possible causes of OBDII code U1503 in a Chrysler vehicle?

- Possible causes include faulty wiring or connections, a malfunctioning FCM, software issues, or a communication error between modules in the vehicle.

4. How do I diagnose OBDII code U1503 in my Chrysler?

- Diagnosis typically involves using a scan tool to read the code, checking for other related codes, inspecting wiring and connections, and testing the FCM and related components.

5. Can I drive my Chrysler with OBDII code U1503?

- It is not recommended to drive the vehicle with unresolved OBDII code U1503, as it may lead to further electrical system issues or drivability problems.

6. How can I repair OBDII code U1503 in my Chrysler?

- Repair steps may include checking and repairing wiring connections, replacing the Front Control Module if necessary, updating software, and clearing the code with a scan tool.

7. Is it safe to clear the OBDII code U1503 without fixing the underlying issue?

- Clearing the code without addressing the root cause may temporarily turn off the warning light, but the issue will likely reoccur, potentially causing further problems.

8. Can a DIY enthusiast fix OBDII code U1503 in a Chrysler?

- Depending on the skill level and tools available, some DIY enthusiasts may be able to address simpler causes like loose connections, but complex issues may require professional diagnosis and repair.

9. Does OBDII code U1503 affect the vehicle's emissions or performance?

- While the code itself may not directly impact emissions, unresolved issues related to U1503 can affect the vehicle's performance and potentially lead to increased emissions over time.

10. How much does it cost to repair OBDII code U1503 in a Chrysler at a dealership or repair shop?

- Repair costs can vary depending on the specific cause of the code, but expect to pay for diagnostics, parts, and labor, potentially ranging from a few hundred to a few thousand dollars.

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