John Deere 001939.05 – SCU: SCV Solenoid Current Low or Comm Error

The Selective Control Valve Control Unit (SCU) has detected that the electrical current drawn by the SCV III (Selective Control Valve #3) flow control solenoid is below the normal operational range. This low current condition can be caused by a blown fuse, a faulty solenoid, or a wiring problem, and triggers a 'Dealer Repair at Earliest Convenience' message to prevent potential loss of hydraulic function for that specific valve.

• 7630
• 7720
• 7730
• 7820
• 7830
• 7920
• 7930
• 8130
• 8230
• 8330
• 8430
• 8530
• 9230
• 9330
• 9430
• 9530
• 9630

1. 1

   Restart the tractor to see if the communication-related fault code clears

2. 2

   Check fuse F13 (for ACU communication issues) and fuse F30 (for SCV solenoid voltage problems) located in the cab fuse box

3. 3

   Inspect wiring harnesses and connectors associated with the SCU, ACU, and SCV solenoids for damage, corrosion, or loose connections

4. 4

   For CAN bus communication errors, test resistance between pins C & D of the diagnostic connector with the battery disconnected (should be 60 ohms; 120 ohms indicates a missing or damaged terminating resistor)

5. 5

   For 'Solenoid Current Low' faults, test the SCV solenoid by activating the function to listen for an audible click, verifying it receives 12 volts, and measuring coil resistance (Parker solenoids should be ~5.6 ohms, Delta valves ~6.2 ohms)

1. 1

   Replace blown fuses

   If fuse F13 or F30 is blown, replace it with a new fuse of the exact same amperage.

2. 2

   Repair CAN bus wiring

   If diagnosing a communication issue (ACU message missing) and fuses are intact, repair any damaged CAN bus wiring. If wiring is good, further control unit diagnostics by a qualified technician are required.

3. 3

   Access and identify SCV solenoid

   For solenoid current faults, clean the area around the SCV stack at the rear of the tractor to prevent contamination, then identify the faulty solenoid (e.g., SCV III).

4. 4

   Replace SCV solenoid

   Disconnect the electrical connector, unscrew the retaining nut, remove the coil, and unscrew the valve stem from the block (expect hydraulic fluid leakage). Install the new solenoid by reversing these steps.

5. 5

   Flush hydraulic system

   Flush the hydraulic system to remove any potential contaminants introduced during the solenoid replacement.

6. 6

   Calibrate SCV

   Recalibrate the SCV through the tractor's diagnostic interface. This procedure may require a John Deere technician.

7. 7

   Replace SCU controller

   If the previous steps do not resolve the issue, the problem may be with the SCU controller itself. Replacing the SCU is a more involved process that typically requires programming by a dealer.