John Deere 523701.05 – BCU / HCC: M08 Stepper Motor for Hitch (Coil 2), Open Circuit

The control unit has detected an abnormally high voltage at the outputs to the stepper motor for the hitch (specifically coil 2) on leads 7054 and 7055. This high voltage reading indicates a discontinuity (open circuit) in the electrical path. Because the circuit is open, current cannot flow properly, which disables the functionality of the stepper motor that controls the rockshaft/rear hitch positioning.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 6140M
• 1654
• 1854
• 2054
• 2104
• 6230
• 6330
• 6430
• 5080R
• 5090R
• 5100R
• 6165J
• 6185J
• 6205J
• 6210J
• 6090MC
• 6100MC
• 6110MC
• 6090RC
• 6100RC
• 6110RC

1. 1

   Inspect the wiring harness and connectors associated with the M08 Stepper Motor (specifically leads 7054 and 7055) for any signs of disconnection, corrosion, wire chafing, or physical damage.

2. 2

   Use a multimeter to test for electrical continuity and voltage in the circuit between the BCU/HCC and the stepper motor. A lack of continuity confirms the open circuit.

3. 3

   Test the internal resistance of the M08 Stepper Motor coils. If Coil 2 shows an infinite resistance, the motor itself has an internal open circuit and has failed.

1. 1

   Disconnect Power

   Disconnect the tractor's battery power before servicing to protect the electronic control units.

2. 2

   Repair Wiring (If Applicable)

   If the diagnostic checks revealed a broken wire or damaged connector on leads 7054/7055, repair the wiring or replace the connector pigtail. Ensure all repairs are properly insulated and secured.

3. 3

   Replace the Stepper Motor (If Applicable)

   If the wiring is intact but the motor is internally open, remove the defective M08 Stepper Motor from the rockshaft control valve assembly and install the replacement motor.

4. 4

   Restore Power and Clear Codes

   Reconnect the battery. Access the tractor's diagnostic menu or use John Deere Service ADVISOR to clear the 523701.05 fault code from the BCU/HCC.

5. 5

   Calibrate the Hitch

   The new stepper motor and hitch system must be calibrated. This is typically done using the Service ADVISOR diagnostic tool or via the tractor's performance monitor calibration procedures.

6. 6

   Test Operation

   Operate the rear hitch through its full range of motion to ensure the stepper motor functions correctly and the draft control responds accurately.