BCU 523691.04 – Lower Worklights on Cab Frame On, Current Too High at Power Module (HF) PC6. John Deere System Advisory.

BCU 523691.04 (BCU )

Code: 523691.04



Error code BCU 523691.04 is activated when the Power Module (High Frequency) PC6 in a John Deere vehicle detects a current exceeding 15 amps at lead 1034 while the lower worklights on the cab frame (E20 or E36) are switched on. This diagnostic trouble code suggests a short to ground in the circuit, a serious issue that can lead to excessive current draw, potentially causing overheating, damage to electrical components, or even a fire hazard.


The power module may respond by limiting or cutting off power to the affected circuit to prevent damage, resulting in the worklights not functioning or operating intermittently.


  • Inspect Wiring and Connections: Examine the wiring harness for the lower worklights to identify any damaged, frayed, or exposed wires that could be causing a short to ground.
  • Check Worklight Fixtures: Look at the worklight fixtures themselves for any signs of damage or corrosion that might contribute to a short circuit.
  • Measure Current and Test for Shorts: Use a multimeter or a clamp meter to measure the current flowing through lead 1034 when the worklights are activated. Additionally, test for continuity between the power lead and ground to confirm the presence of a short.
  • Repair or Replace Faulty Wiring or Components: Replace any damaged wiring or components identified during the inspection. Ensure all connections are secure and properly insulated to prevent future shorts.
  • Reset the Power Module PC6: After making the necessary repairs, reset the power module to ensure that it recognizes the repairs and to clear any protective settings that were triggered by the high current condition.
  • Test System Functionality: After the reset, test the worklights to ensure they are functioning correctly without triggering a high current draw. Monitor the system to verify stability.
  • Continuous Monitoring: Keep an eye on the affected circuit, especially immediately after repairs, to ensure there are no recurring issues. Consider implementing regular inspections as part of the vehicle’s maintenance schedule.


Electrical safety in vehicle systems is crucial, particularly in components that draw significant power, like worklights. Preventing and addressing shorts in electrical circuits are key to ensuring the safety and reliability of the machinery. Regular maintenance checks and immediate action on any signs of electrical issues are essential practices to maintain the operational integrity and safety of the vehicle.