John Deere 523893.18 – Rear Chassis Module (SCC) / SIC: SCV 4 Valve Low Voltage / A39 Stepper Motor ESCV 4, Hydraulic Oil Temperature and Supply Voltage Too Low

Selective Control Valve IV (SCV 4) is inoperative. The system has detected that the supply voltage to the A39 stepper motor controlling the valve is too low, or the hydraulic oil temperature is too cold for the valve to operate correctly. Tractor-Implement Automation may be deactivated.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 7430
• 7530

1. 1

   Wait until the hydraulic oil has warmed up to normal operating temperature (cold oil can trigger this code)

2. 2

   Check and clean the ISOBUS connection between the tractor and the implement

3. 3

   Inspect the wiring and connectors between the SCC/SIC control unit and the ESCV 4 stepper motor (A39) for damage, wear, corrosion, or loose connections

4. 4

   Measure the supply voltage at the A39 stepper motor connector using a multimeter

1. 1

   Warm up hydraulic oil

   Start the tractor and allow the hydraulic oil to reach normal operating temperature. If the code clears and SCV 4 resumes operation, no further repair is needed.

2. 2

   Disconnect harness

   If the code persists with warm oil, disconnect the harness at the SCV 4 stepper motor (A39).

3. 3

   Test supply voltage

   Test the supply voltage at the connector pins. If the voltage is low or absent, trace the wiring harness back to the Rear Chassis Module (SCC) or SIC controller, repairing any broken wires, chafing, or corroded pins.

4. 4

   Diagnose stepper motor

   If the wiring harness and voltage supply are verified to be good, the fault lies within the A39 E-SCV stepper motor itself (internal failure or loss of communication).

5. 5

   Replace stepper motor

   Remove the faulty stepper motor from the SCV 4 valve slice and install a replacement.

6. 6

   Inspect valve spool

   If the valve spool itself is binding and causing the motor to fail, the entire SCV valve slice may need to be replaced or rebuilt.

7. 7

   Clear codes and verify

   Clear the diagnostic trouble codes using Service ADVISOR or the tractor's display, and cycle the SCV 4 controls to verify the repair.