BCU 523691.01 – Lower Worklights on Cab Frame, Incorrect Supply Voltage at Power Module (HF) PC6. John Deere System Advisory.

BCU 523691.01 (BCU )

Code: 523691.01



Error code BCU 523691.01 is triggered when the Power Module (High Frequency) PC6 in a John Deere vehicle measures less than 3 volts at the supply voltage for the lower worklights on the cab frame (E20 or E36), when these lights are activated. This diagnostic trouble code indicates a potential issue with the power supply circuit, such as a poor connection, insufficient voltage from the power source, or a fault within the power module itself, which prevents the worklights from receiving adequate power for operation.


The low voltage condition may cause the worklights to fail to illuminate or to operate at reduced efficiency, potentially compromising visibility and safety during operations that require enhanced lighting.


  • Inspect the Power Module PC6 and Wiring: Check the power module and the wiring leading to the worklights for signs of damage, corrosion, or loose connections that could be causing the low voltage issue.
  • Measure Voltage at Power Supply: Use a multimeter to measure the voltage at lead 0732 when the worklights are activated. This will help confirm if the voltage is indeed below the required threshold.
  • Test Power Source: Evaluate the overall health and output of the vehicle’s electrical system to ensure it is capable of providing adequate voltage to the power module.
  • Repair or Replace Faulty Components: If any components of the power module or wiring are found to be defective, repair or replace them to restore proper voltage supply to the worklights.
  • Reset the Power Module PC6: After repairs, reset the power module to ensure that it can accurately control and supply power to the worklights. Clear any related diagnostic trouble codes.
  • Test Worklights Functionality: Following the reset and repairs, test the worklights to ensure they receive appropriate power and function correctly under all operating conditions.
  • Monitor System Post-Repair: Continue to monitor the system to ensure no further issues with the supply voltage occur. Regular checks can help prevent similar issues from affecting the vehicle’s operation.


Maintaining proper voltage levels in vehicle electrical systems is crucial for the operation of critical components such as worklights. These systems require regular inspection and maintenance to ensure they function efficiently and safely. Addressing electrical issues promptly helps maintain operational readiness and ensures the safety of those operating or working around the machinery.