John Deere SCO523663.05 – SCO: Auxiliary Valve Current Problem

This fault code indicates an electrical issue with the auxiliary valve solenoid circuit, specifically that the current is below the normal range or the circuit is open (indicated by FMI .05). This is typically caused by a failed solenoid coil, damaged wiring, or a poor connection, which prevents the Secondary Hydraulic Control Unit (SCO) from properly managing auxiliary hydraulic functions.

• 7630
• 7720
• 7730
• 7820
• 7830
• 7920
• 7930
• 8120
• 8220
• 8320
• 8420
• 8520
• 9120
• 9220
• 9230
• 9320
• 9320T
• 9330
• 9420
• 9420T
• 9430
• 9520
• 9520T
• 9530
• 9620
• 9620T
• 9630

1. 1

   Restart the tractor to see if a temporary communication glitch clears the code

2. 2

   Inspect fuses related to the hydraulic control units, specifically F29, F51, F12, and F24

3. 3

   Visually inspect battery terminals, alternator, and surrounding wiring for corrosion, damage, or accumulated debris

4. 4

   Inspect wiring harnesses and connectors leading to the auxiliary hydraulic valves for visible damage

5. 5

   With the tractor on and auxiliary hydraulic function activated, check for voltage at the connector for the suspect solenoid

6. 6

   Disconnect the solenoid and measure resistance across its terminals, comparing to a known-good solenoid (an open or short circuit indicates a faulty solenoid)

7. 7

   Check for continuity and signs of a short to ground in the wiring harness between the SCO controller and the auxiliary valve solenoid

1. 1

   Perform initial diagnostics

   Restart the tractor, check fuses F29, F51, F12, and F24, and visually inspect wiring and connectors to rule out simple causes.

2. 2

   Isolate the faulty component

   Test the auxiliary valve solenoid for proper voltage and resistance. Inspect the wiring harness for continuity or shorts to ground.

3. 3

   Replace the faulty component

   Replace the solenoid if it fails resistance testing, or repair/replace damaged wiring. If the SCO controller is suspected, have it diagnosed and replaced by a qualified technician as it may require programming.

4. 4

   Clear fault codes

   After repairs are complete, clear the fault codes from the system.

5. 5

   Test operation

   Operate the auxiliary hydraulic functions to ensure the repair was successful and the fault code does not return.