BCU 523691.01 – Incorrect Supply Voltage for Lower Worklights on Cab Frame. John Deere System Advisory.

BCU 523691.01 (BCU )

Code: 523691.01



Error code BCU 523691.01 is activated when the power module (HF) PC6 detects a supply voltage of less than 3 volts at output (lead 0732) for the worklights on the cab frame (E20 or E36), while these worklights are turned on. This low voltage condition indicates a possible issue in the power supply circuit or the electrical connections leading to the worklights.


The power module will likely prevent the worklights from operating to protect the system against potential damage caused by insufficient voltage, which could otherwise lead to inefficient lighting performance or electrical instability.


  • Inspect Wiring and Connectors: Begin with a thorough inspection of the wiring and connectors leading to the worklights. Look for any signs of damage, corrosion, or loose connections that might be causing the low voltage issue.
  • Test Voltage Levels: Use a multimeter to measure the voltage levels at various points along the circuit to identify where the drop in voltage occurs.
  • Repair or Replace Faulty Components: If specific components or sections of wiring are found to be faulty, repair or replace them to ensure the correct voltage is supplied to the worklights.
  • Check Ground Connections: Ensure that all ground connections are secure and free of corrosion, as poor grounding can also contribute to voltage issues.
  • Verify System Functionality: After repairs are made, check that the worklights and other related systems are receiving appropriate voltage and are functioning correctly.


Maintaining proper voltage levels is crucial for the reliable operation of vehicle electrical systems. Regular checks and maintenance can help prevent issues related to incorrect voltage supply, thereby ensuring that all electrical components function as intended and reduce the risk of operational disruptions.