BCU 523921.00 – E11/2 /E31R Worklights on Rear of Roof, Current Overload Protection Active. John Deere System Advisory.

BCU 523921.00 (BCU )

Code: 523921.00



Diagnostic trouble code BCU 523921.00 is activated when the power module PC0 detects that the total amperage exceeds 40 amps at the B3, C3, and D3 outputs. These outputs are associated with various worklights and lights on the rear and sides of the roof, specifically:

  • Output B3: E11/2 /E31R Worklights on Rear of Roof.
  • Output C3: E31L Xenon (HID) Worklights on Rear of Roof.
  • Output D3: E07 Left Light on Cab Frame (Low Beam). This high current condition typically indicates a short to ground or a defective component within one or more of the circuits involved, prompting the activation of current overload protection to prevent further damage and potential safety hazards.


The system responds by activating current overload protection, likely resulting in the shutdown of the affected circuits to prevent electrical damage or fire risk. Alerts or warnings may be issued to inform the operator of the overload condition, necessitating immediate attention and corrective action.


  • Inspect Wiring and Connectors: Thoroughly examine the wiring and connectors for outputs B3, C3, and D3. Look for signs of damage, wear, or corrosion that could be causing the excessive current.
  • Test Electrical Components: Utilize electrical testing tools to check the worklights and other components connected to these outputs for shorts or other faults.
  • Replace or Repair Faulty Components: If specific components or sections of wiring are found to be faulty, replace or repair them to restore proper functionality and prevent further issues.
  • Reset and Monitor the System: After making repairs, reset the power module and monitor the system to ensure that the current levels have returned to normal and that no further overload conditions occur.
  • Review Additional Diagnostic Codes: Since this issue may trigger related diagnostic codes, review and resolve any additional codes that appear as a result of this overload condition to ensure comprehensive resolution.


Regular monitoring and maintenance of the electrical components involved in the worklight systems are crucial for ensuring the safe and efficient operation of agricultural machinery. Addressing current overload issues promptly helps maintain operational efficiency and prevent damage to the machinery, thereby minimizing downtime and enhancing equipment longevity.

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