ETC 001079.04 – 5volt Power Supply, Voltage Too Low

ETC 001079.04 (ETC 1079.04)

Code: 001079.04

Shortcode: 1079.04


The error code ETC 001079.04 is triggered when the voltage measured at the positive lead (lead 2093) of the power supply to the 5-volt components (refrigerant pressure sensor B130, heater valve B131, and motor for adjusting the air distribution flaps B132) is less than 0.5 volts. This indicates a short to ground in the circuit.


When this fault is detected, the control unit may disable or limit the operation of the 5-volt components to prevent malfunction due to undervoltage. This can result in the malfunction of the refrigerant pressure sensor, heater valve, and air distribution flap motor.


Inspect Electrical Circuits:

  • Check for Shorts to Ground: Inspect the wiring and connectors for signs of short circuits to ground. Look for damaged insulation, exposed wires, or pinched cables.
  • Measure Voltage: Use a multimeter to measure the voltage at the positive lead (lead 2093) to ensure it is within the specified range.

Test and Replace Components:

  • Test 5-Volt Components: Verify the operation of the refrigerant pressure sensor B130, heater valve B131, and motor B132. Replace any components that are found to be malfunctioning due to undervoltage.
  • Inspect Control Unit: Ensure that the control unit is functioning correctly. Replace the control unit if it is found to be faulty.

Repair or Replace Wiring:

  • Fix Damaged Wiring: Repair or replace any damaged or shorted wiring in the 5-volt power supply circuit. Ensure all connections are secure and properly insulated.


Maintaining the integrity of the electrical connections is crucial for the reliable operation of the 5-volt components. Regular inspection and timely repairs of the electrical system can help prevent issues related to undervoltage.

Control Units: John Deere

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