BCU 523691.05 – No Current Detected in Lower Worklights on Cab Frame. John Deere System Advisory.

BCU 523691.05 (BCU )

Code: 523691.05



This diagnostic trouble code, BCU 523691.05, is triggered when the power module (HF) PC6 detects a current of less than 500 mA at the output for the lower worklights on the cab frame (E20 or E36), specifically in lead 1034, while these lights are switched on. Such a low current measurement typically indicates an open circuit, which means there is a disconnection or break somewhere within the circuit.


Upon detection of an open circuit, the system will likely deactivate the affected worklights to prevent any further electrical inconsistencies and alert the operator to the malfunction.


  • Inspect Wiring and Connectors: Thoroughly check the wiring and connectors involved in the affected circuit. Look for disconnections, breaks, or damage that might have caused the open circuit.
  • Test for Continuity: Use a multimeter to test for continuity within the circuit. This helps identify the specific location of the open circuit.
  • Repair or Replace Faulty Wiring: If breaks or disconnections are found, repair or replace the faulty wiring to restore proper circuit function.
  • Ensure Secure Connections: Check that all connectors and terminals are secure and properly engaged to prevent future occurrences of open circuits.
  • Verify System Functionality: After repairs, test the worklights and circuit to ensure that current is flowing appropriately and that the worklights are operational again.


Preventive maintenance and regular checks of electrical systems are essential for ensuring the reliability and safe operation of vehicle systems. Addressing issues such as open circuits quickly helps maintain operational efficiency and prevents potential safety hazards.