OIC 521423.08 – Left Brake Pedal Position, Fault (XMB/XMC Messages Missing)

OIC 521423.08 (OIC )

Code: 521423.08



This error code is generated when the left brake pedal sensor unit transmits an incorrect signal to the control software. This can occur due to a frozen heartbeat from XMB/XMC control units, indicating communication issues.


The control software may function in a limited capacity or not at all, affecting the operation of the left brake pedal sensor unit.


Inspect Brake Pedal Sensor:

  • Check the left brake pedal sensor unit and its wiring for signs of damage, loose connections, or corrosion. Repair or replace any faulty components.

Test Sensor Output:

  • Use a multimeter to measure the voltage output of the left brake pedal sensor. Ensure it is within the valid range.

Verify Communication:

  • Ensure that the XMB/XMC control units are functioning correctly and are communicating properly with the brake pedal sensor. Check for any communication errors or disruptions.

Update Control Software:

  • Ensure that the control software is updated to the latest version. Firmware updates might include improvements in handling sensor signals and communication.

Consult Manufacturer Support:

  • If the issue persists, consult technical support or the manufacturer for further diagnostics and assistance.

Monitor System Performance:

  • After addressing the issue, monitor the system to ensure the left brake pedal sensor functions correctly and the error does not recur.


Reliable communication between control units and sensors is crucial for vehicle operation. Regular maintenance and updates can prevent issues related to signal transmission and reception.

Control Units: John Deere

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