John Deere 000924.04 – SCO: Low Voltage On Rear SCV Valves
Issue description
The system has detected a low voltage condition (SPN 924, FMI 4) related to the operation of rear Selective Control Valves (SCV) 10 and 11. This indicates an insufficient electrical supply to the solenoids that control these SCV valves, which can impede their proper function. The Secondary Hydraulic Control Unit (SCO), also known as the Front Chassis Module, is responsible for monitoring and controlling this condition.
Applies to these machines
11 machines- 8120
- 8220
- 8320
- 8420
- 8520
- 9120
- 9220
- 9320
- 9420
- 9520
- 9630
Check the cause
Attempt initial system recovery by reducing overall electrical load, increasing engine RPM to boost alternator output, or cycling the tractor's power to clear temporary faults
Check for other related diagnostic trouble codes to determine if this is a systemic electrical issue or a localized problem
Conduct a visual inspection of battery terminals, battery cables, and alternator connections for corrosion, damage, or loose connections. Ensure the area around the alternator is free of debris.
Check Fuse F29, which is critical for the switched power supply to the auxiliary valve solenoids
Repair steps
Address immediate visual findings
Clean corroded battery or alternator terminals, tighten loose connections, and replace Fuse F29 if it is blown.
Test alternator output
If no obvious visual issues are found, test the alternator's output to ensure it is charging the battery correctly. A low system voltage warning can indicate a failing alternator.
Inspect wiring harness
If power supply components are functioning correctly, inspect the wiring harness leading to the SCO controller and the SCV valve solenoids. Look for chafed, pinched, or damaged wires that could cause a short or intermittent connection.
Isolate and test the solenoid
If the low voltage issue persists and is isolated to the SCV valves, the valve's solenoid coil may be faulty and drawing excessive current. Test the resistance of the solenoid or swap it with a known good solenoid from another SCV to see if the fault follows the component.
Parts you might need
(5)Electro-mechanical valves control fluid flow and are a common failure point. Verify compatibility with specific machine's parts catalog.
Electro-mechanical valves control fluid flow and are a common failure point. Verify compatibility with specific machine's parts catalog.
Less common failure but should be considered if all other diagnostic steps fail. Replacement often requires calibration by a John Deere dealer.
Less common failure but should be considered if all other diagnostic steps fail. Replacement often requires calibration by a John Deere dealer.
Less common failure but should be considered if all other diagnostic steps fail. Replacement often requires calibration by a John Deere dealer.
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