John Deere 521001.07 – HCC (Hitch Control Computer) / HCU (Hitch Control Unit): Rear Hitch Control Valve Circuit Fault / HCU Calibration Fault / Rear Hitch Raise Solenoid

The control module has detected a circuit problem or a calibration error specifically related to the rear hitch raise pressure valve/solenoid. The raise valve is typically flagged as 'not calibrated,' and the automatic hitch functions may be disabled, though the hitch will often still work in manual mode.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 5065M
• 5075M
• 5085M
• 5115ML
• 5095M
• 5095MH
• 5105M
• 5015ML
• 7630
• 7720
• 7730
• 7820
• 7830
• 7920
• 7930
• 8245R to 8400R
• 8310RT
• 8335RT
• 8360RT
• 9230
• 9330
• 9430
• 9530
• 9630

1. 1

   Restart the tractor to verify if the code is a hard fault or a temporary communication glitch.

2. 2

   Check if the rear hitch operates using the manual external switches.

3. 3

   Inspect the wiring harness and connectors at the rear hitch control valve for damage, corrosion, or loose pins.

4. 4

   Verify that the hydraulic oil level is adequate, as low fluid can cause secondary hydraulic faults.

1. 1

   Relieve Pressure

   Turn off the tractor and relieve all hydraulic pressure from the rear hitch system.

2. 2

   Inspect and Test the Solenoid

   Locate the rear hitch control valve block. Disconnect the wiring harness from the raise solenoid. Test the solenoid coil for proper resistance and verify that the harness is delivering the correct voltage.

3. 3

   Replace Faulty Components

   If the solenoid coil is shorted, open, or physically damaged, replace the solenoid coil. If the valve spool itself is sticking or damaged, the entire hitch control valve assembly may need replacement.

4. 4

   Reconnect and Clear Codes

   Securely reconnect the wiring harness. Turn the key on and use the CommandCenter or diagnostic display to clear the stored 521001.07 code.

5. 5

   Perform Hitch Calibration

   Perform the Rear Hitch Calibration procedure using the tractor's display monitor or dealer diagnostic software to relearn the valve's parameters.