ETC 523979.07 – S139 Switch for Heated Rear Window, Fault

ETC 523979.07 (ETC )

Code: 523979.07



The error code ETC 523979.07 is triggered when the control unit receives the engagement signal of the rear window heater switch (S139) for too long a period of time. This indicates that the switch is jammed, defective, or there is a problem in the circuit.


When this fault is detected, the control unit may disable the rear window heater to prevent continuous operation. This can lead to the rear window heater not functioning as intended.


Inspect Electrical Circuits:

  • Check for Continuous Signal: Inspect the wiring and connectors for the rear window heater switch (S139) for signs of a continuous signal. Look for damaged insulation, exposed wires, or pinched cables.
  • Measure Signal Duration: Use a multimeter to measure the duration of the engagement signal at lead 2013 to ensure it is within the specified range.

Test and Replace Components:

  • Test Rear Window Heater Switch: Verify the operation of the rear window heater switch (S139). Replace the switch if it is found to be jammed or defective.
  • 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 Circuit Problems: Repair or replace any damaged or faulty wiring in the rear window heater switch circuit. Ensure all connections are secure and properly insulated.


Regular maintenance and inspection of the rear window heater switch and its associated wiring can help prevent issues related to continuous signals. Ensuring proper operation and connectivity will enhance system reliability and performance.

Control Units: John Deere

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