BCU 523919.01 – Inner Worklights on Front of Roof, Power Supply Fault. John Deere System Advisory.

BCU 523919.01 (BCU )

Code: 523919.01



Diagnostic trouble code BCU 523919.01 is generated when the power module PC0 measures a supply voltage of less than 3 volts at lead 0802 for the inner worklights on the front of the roof while they are switched on. This low voltage reading indicates a power supply fault in the circuit that supplies these lights, potentially due to issues such as wiring defects, connection failures, or component malfunctions within the power distribution system.


The system may prevent the inner worklights from operating due to insufficient voltage, which could impair visibility if these lights are required for operation in low-light conditions. An alert may be displayed to inform the operator of the insufficient power supply, prompting immediate troubleshooting.


  • Inspect Wiring and Connections: Examine the wiring and electrical connections for lead 0802. Look for signs of damage, wear, or corrosion that could be causing voltage drops.
  • Measure and Verify Voltage Levels: Use a multimeter to measure the voltage at the output for the inner worklights. This will confirm the low voltage condition and help in diagnosing the point of failure.
  • Check for Voltage Drops: Test the voltage along the circuit to identify any points where significant voltage drops occur, indicating potential resistance or faults.
  • Replace or Repair Faulty Components: If any damaged wires or faulty electrical components are found, replace or repair these to ensure proper voltage supply to the worklights.
  • Reset the System and Test: After making the necessary repairs, reset the electrical system to clear any fault codes and test the worklights to ensure they are receiving the correct voltage and functioning properly.


Maintaining the electrical integrity of worklight systems is crucial for safety, especially when operating machinery in poorly lit environments. Regular electrical system checks should be part of the routine maintenance schedule to prevent issues such as voltage drops that can lead to operational inefficiencies and potential safety hazards. Properly functioning worklights enhance visibility, allowing for safe and efficient machinery operation under all conditions.

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