BCU 523691.12 – Lower Worklights on Cab Frame Off, Current Present at Power Module (HF) PC6. John Deere System Advisory.

BCU 523691.12 (BCU )

Code: 523691.12



Error code BCU 523691.12 is activated when the Power Module (High Frequency) PC6 in a John Deere vehicle detects a current exceeding 1 amp at lead 1034 for the lower worklights on the cab frame (E20/R and E20/L) or the xenon (HID) worklights on the cab frame (E36/R and E36/L), even though these lights are switched off. This diagnostic trouble code suggests the presence of a short in the circuit or an internal fault within the power module itself, which can lead to unnecessary power consumption and potential overheating or damage to the electrical system.


The system may automatically attempt to reduce the risk of damage by limiting or cutting power to the affected circuits. This protective action helps prevent further electrical issues but results in the worklights remaining non-operational.


  • Inspect Worklight Circuits: Check the wiring and connections for the lower and xenon (HID) worklights on the cab frame. Look for any signs of damage, fraying, corrosion, or improper connections that could cause a short circuit.
  • Measure Current Flow: Use a clamp meter or multimeter to measure the current flow through lead 1034 to accurately assess the situation and confirm the overcurrent condition.
  • Identify and Repair Short Circuits: Locate and repair any shorts to ground or other circuit faults found during the inspection. This may involve replacing damaged wires or connectors.
  • Evaluate Power Module PC6: Check the power module for any signs of internal faults that could be causing it to output current erroneously. Replace if necessary.
  • Reset the Power Module and BCU: After making the necessary repairs or replacements, reset both the power module and the BCU to ensure all system settings are updated and the error codes are cleared.
  • Test System Functionality: Activate the worklights to ensure they are functioning correctly without drawing excess current when switched off. Continue to monitor the system to confirm that the issue has been fully resolved.
  • Regular Monitoring and Maintenance: Incorporate regular checks of the electrical system into routine maintenance procedures to catch and correct any emerging issues before they lead to system failures.


Maintaining the electrical integrity of vehicle lighting and power systems is crucial for safe operation. Regular inspections and proactive maintenance can help prevent issues like shorts and internal faults, ensuring that lighting systems function efficiently and safely. This approach not only preserves the vehicle’s operational capabilities but also enhances safety by preventing potential electrical hazards.