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

The left brake pedal position sensor unit transmits an incorrect signal to the control software. This is typically a communication failure (such as a frozen heartbeat or missing messages from the XMB/XMC control units on the CAN Bus) which prevents the system from accurately reading the pedal's position.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 9470RT
• 9520RT
• 9570RT
• 8245R through 8400R

1. 1

   Inspect the left brake pedal position sensor and its wiring harness for signs of physical damage, loose connector pins, or corrosion

2. 2

   Use a multimeter to measure the voltage output of the left brake pedal sensor as the pedal is depressed to ensure it is operating within its valid sweep range

3. 3

   Check the CAN Bus lines between the OIC and the XMB/XMC control units for continuity, shorts, or communication disruptions

4. 4

   Ensure the OIC control software is updated to the latest firmware version

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Resolve Wiring/Communication Issues

   If the diagnostic checks revealed damaged wiring or a poor connection at the OIC or XMB/XMC harness, repair the wiring or replace the damaged connector.

3. 3

   Replace the Sensor

   If the wiring and CAN bus communication are intact but the sensor failed the multimeter sweep test, remove the mounting hardware for the left brake pedal position sensor and install a new OEM sensor.

4. 4

   Reassemble and Restore Power

   Reconnect the sensor harness and restore battery power.

5. 5

   Calibrate the Sensor

   Calibrate the new brake pedal position sensor via the John Deere Service ADVISOR tool to prevent related codes.

6. 6

   Clear Codes and Test

   Clear the OIC 521423.08 code from the system and test the left brake pedal operation to ensure the code does not return.