BCU 000168.04 – Control Unit Supply Voltage Too Low. John Deere System Advisory.

BCU 000168.04 (BCU 168.04)

Code: 000168.04

Shortcode: 168.04


Error code BCU 000168.04 is triggered when the Basic Control Unit (BCU) of a John Deere vehicle detects a supply voltage that falls below 12 volts. This low voltage condition can impair the functionality of the vehicle’s electrical systems, potentially leading to diminished performance, failures in electronic component operations, and inability to start the engine.


In response to the low voltage, the BCU may reduce the performance of non-critical systems or display warning indicators on the dashboard to alert the operator of the voltage issue.


  • Inspect Battery and Charging System: Begin by checking the vehicle’s battery for adequate charge and health. Ensure the alternator and charging system are functioning correctly to maintain proper voltage levels.
  • Check Wiring and Electrical Connections: Examine all related wiring and connections for corrosion, damage, or looseness that might contribute to voltage drops. Repair or replace any faulty components.
  • Test Voltage Levels: Use a multimeter to verify the voltage at the BCU supply input and across various points in the electrical system to pinpoint areas of significant voltage drop.
  • Replace or Recharge Battery: If the battery is unable to hold a charge, it may need to be replaced. If the battery is simply discharged, recharge it and investigate any potential causes for the drain.
  • Reset and Recalibrate the BCU: After addressing the issues causing low voltage, reset the BCU to clear any fault codes and recalibrate any systems that may have been affected by the low voltage conditions.


Adequate supply voltage is critical for the safe and efficient operation of all vehicle systems. Regular checks of the electrical system, including the battery and alternator, are vital to prevent issues associated with low voltage. Timely maintenance and repairs can help ensure continuous and reliable operation of your John Deere equipment, avoiding unexpected downtime and costly repairs.