FCC 000158.17 – Instrument Unit, Supply Voltage (ELX) Too Low

ETC 000158.17 (ETC 158.17)

Code: 000158.17

Shortcode: 158.17


This error code indicates that the supply voltage to the Instrument Unit (ELX) has fallen below 11.2 volts while the engine speed is below 500 RPM. This could be due to a weak battery, poor electrical connections, or issues with the charging system.


The control software will have limited or no functionality due to the undervoltage condition, affecting the reliability and accuracy of the instrument unit’s readings.


  • Check Battery Health: Ensure the battery is not weak or discharged and is capable of holding a charge.
  • Inspect Charging System: Verify that the charging system is functioning correctly even at low engine speeds.
  • Examine Wiring and Connections: Look for any loose, corroded, or damaged wires and connections that could be causing a voltage drop.
  • Test Voltage Under Load: Use diagnostic tools to test the voltage levels under different engine loads to identify the source of the undervoltage.


Undervoltage conditions can lead to inaccurate data from the Instrument Unit, potentially causing operational issues. Regular inspections and maintenance of the electrical system are essential to prevent such faults.

Control Units: John Deere

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