John Deere 925.04 – SCO: Stepper Motor for E-SCV XII, Supply Voltage Too Low

The voltage at the stepper motor input for the Electronic Selective Control Valve (E-SCV XII) has fallen below 9 volts. This condition typically suggests a potential short to ground or a failing power supply circuit, which prevents the stepper motor from operating correctly. When this fault is detected, the control software will limit or completely disable the function of the affected selective control valve (E-SCV XII).

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6140R
• 6150R
• 6230R
• 6250R
• 6090M
• 6100M
• 6110M
• 6120M
• 6130M
• 6140M
• 6145M
• 6155M
• 6175M
• 6195M
• 5090R
• 5100R
• 5115R
• 5125R

1. 1

   Monitor Voltage: Use a multimeter or John Deere Service Advisor to continuously monitor the voltage at the stepper motor input to see if it is consistently below the 9-volt threshold.

2. 2

   Inspect Wiring for Shorts: Trace the wiring harness connected to the E-SCV XII stepper motor. Look for any signs of chafing, melted insulation, or exposed wires that could be causing a short to ground.

3. 3

   Check Electrical Connections: Inspect the plug and pins at the stepper motor and the SCO controller. Look for corrosion, moisture ingress, looseness, or bent pins. Clean and secure the connections as needed.

4. 4

   Verify Power Supply: Ensure that the main power supply to the stepper motor circuit is stable and within the required voltage range (typically 12V system voltage). If the supply voltage is low at the source, inspect the battery, alternator, and power supply relays.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Relieve Hydraulic Pressure

   Ensure all hydraulic pressure is relieved from the SCV system before working near the valve block.

3. 3

   Access the Valve Block

   Locate the rear SCV valve block and identify the specific E-SCV XII stepper motor.

4. 4

   Disconnect Harness

   Carefully unplug the electrical connector from the stepper motor.

5. 5

   Remove the Stepper Motor

   Unbolt the stepper motor from the SCV housing. Be prepared for minor hydraulic fluid weeping; have shop towels ready.

6. 6

   Clean and Inspect

   Clean the mounting surface on the SCV valve. Inspect the mechanical linkage inside the valve to ensure it moves freely and isn't binding (which can cause the motor to draw excessive current and drop voltage).

7. 7

   Install New Seals

   Install a new SCV flange seal kit to prevent hydraulic leaks.

8. 8

   Install New Motor

   Mount the new stepper motor and torque the bolts to OEM specifications.

9. 9

   Reconnect and Calibrate

   Reconnect the electrical harness, reconnect the battery, and use John Deere Service Advisor to clear the SCO 000925.04 code and calibrate the new E-SCV stepper motor.