John Deere 000186.15 – BCU: Rear PTO Continues Rotating After Disengagement

The Basic Control Unit (BCU) detects that the rear Power Take-Off (PTO) speed is still registered after the PTO has been switched off. The PTO shaft continues to rotate for an extended period after the command to disengage has been given, rather than stopping within a few seconds. This indicates a potential electrical, hydraulic, or mechanical issue preventing the PTO from stopping in a timely manner.

• 6120
• 6120L
• 6220
• 6220L
• 6320
• 6320L
• 6420
• 6420L
• 6420S
• 6520
• 6520L

1. 1

   Retrieve all Diagnostic Trouble Codes (DTCs) to identify any other active or stored faults related to the PTO issue.

2. 2

   Inspect the wiring harness and connectors for the rear PTO speed sensor and the PTO solenoid valve for damage, corrosion, or loose connections.

3. 3

   Check the PTO solenoid valve by listening for an audible 'click' when the PTO switch is engaged. No click indicates an electrical issue (check switch, fuses, relays); a click without proper function suggests a hydraulic or mechanical valve failure.

4. 4

   Test the rear PTO speed sensor (a magnetic pickup that generates an AC signal and does not receive power) by monitoring its input signal for consistency or checking its resistance with a multimeter (expected reading is approximately 550 ohms at 20°C). An open circuit indicates a failed sensor.

5. 5

   Inspect the PTO brake and clutch drum for worn brake facings, warped clutch discs, or out-of-adjustment components if the PTO continues to turn slowly when disengaged.

1. 1

   Replace rear PTO speed sensor

   If the sensor is faulty or has an open circuit, locate it threaded into the rear PTO housing, disconnect the electrical connector, unscrew the old sensor, and install the new sensor tightened to manufacturer specifications. Reconnect the electrical connector, clear fault codes, and test the PTO operation.

2. 2

   Replace PTO solenoid valve

   If the valve is clicking but failing to actuate hydraulically, relieve hydraulic pressure and clean the area to prevent contamination. Disconnect the electrical connector, remove the mounting bolts, and carefully remove the old valve (be aware of leaking fluid). Install the new solenoid valve with new seals and gaskets, ensuring it is properly seated. Torque bolts to spec, reconnect the electrical connector, clear codes, and test the PTO system.

3. 3

   Repair PTO brake assembly

   If the PTO brake is worn or clutch plates are warped (mechanical failure), the tractor must be split to access the PTO clutch and brake assembly. Inspect for worn facings or a sheared anti-rotation pin. Due to complexity, this should be performed by an experienced technician.