John Deere 1079 – RCU: Right Control Unit Sensor Power Voltage Too Low

The voltage supplied by the Right Control Unit (E02) to its associated sensors has dropped below the acceptable threshold (indicated as below 4.5 VDC). This triggers a Priority 2 diagnostic indicator on the Cornerpost Display.

• 9540 WTS
• 9560 STS
• 9560 WTS
• 9580 WTS
• 9640 WTS
• 9650 STS
• 9660 STS
• 9660 WTS
• 9680 WTS
• 9750 STS
• 9760 STS
• 9860 STS
• 9880STS
• S650
• S790
• T550
• T670
• W540
• W660

1. 1

   Access and record all active and stored diagnostic trouble codes using the Cornerpost Display or VISIONTRAK to confirm E02 001079.04 and identify any related codes.

2. 2

   Check for related sensor faults (e.g., hydraulic oil temperature or main gearcase oil temperature), as multiple sensor faults often point to a shared power supply issue from the control unit rather than individual sensor failures.

3. 3

   Visually inspect the wiring harness and connectors associated with the Right Control Unit (typically located in an exterior cab compartment) for damage, corrosion, or loose connections.

4. 4

   If supported by your model (e.g., 9880STS), monitor the live voltage of the Right Control Unit Sensor Power (cc# 781) via the diagnostic display to confirm the low voltage condition.

1. 1

   Inspect and repair wiring

   Disconnect the control unit connectors, wait for 30 seconds, and securely reconnect them. Repair any damaged wiring and ensure all connections to the Right Control Unit are clean and secure.

2. 2

   Clear codes and test

   Clear the fault codes and operate the machine to see if the fault code returns. If it does not, the issue was likely a loose connection.

3. 3

   Replace Right Control Unit

   If the fault persists after verifying the integrity of the external wiring, the issue likely lies within the Right Control Unit itself and it must be replaced.