BCU 523760.04 – Turn Signal/Hazard Flasher System, Supply Voltage Too Low. John Deere System Advisory.

BCU 523760.04 (BCU )

Code: 523760.04



Error code BCU 523760.04 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle detects a supply voltage below 12 volts at the inputs for the turn signal/hazard flasher system. This diagnostic trouble code indicates insufficient voltage to operate the turn signal and hazard flasher system effectively, which could be due to a variety of electrical issues such as a weak battery, poor wiring connections, or a failing alternator.


The low voltage condition may cause the turn signals and hazard lights to function intermittently, dimly, or not at all, potentially compromising the vehicle’s visibility and signaling capabilities on the road or in the field. This poses a safety risk, particularly in low-light conditions or busy operational environments.


  • Inspect Battery and Charging System: Check the vehicle’s battery for proper charge level and health. Inspect the charging system, including the alternator, to ensure it is providing adequate charge to the battery.
  • Test Electrical Connections: Use a multimeter to test the voltage at the inputs of the turn signal/hazard flasher system. Inspect all related wiring and connections for corrosion, damage, or looseness that could contribute to voltage drops.
  • Repair or Replace Faulty Components: If any components of the charging system or wiring are found to be defective, repair or replace them to restore proper voltage levels.
  • Check Ground Connections: Ensure all ground connections related to the turn signal and hazard flasher system are clean, tight, and corrosion-free.
  • Reset the BCU: After addressing the voltage issues, reset the BCU to clear the diagnostic trouble code and reinitialize the system settings.
  • Test System Functionality: After repairs and adjustments, test the turn signal and hazard flasher system to ensure it operates correctly and consistently at the required voltage level.
  • Regular Electrical System Maintenance: Incorporate regular checks of the electrical system into your maintenance schedule to prevent future voltage issues. Regular maintenance helps ensure all electrical systems function reliably and efficiently.


Maintaining the electrical integrity of vehicle systems is crucial for safe operation. Ensuring that all components, particularly those related to safety features like turn signals and hazard flashers, are in good working condition is essential for the visibility and operability of the vehicle. Regular checks and timely repairs of the electrical system can significantly enhance safety and prevent operational disruptions.