John Deere 186.15 – BCU or RPT: Rear PTO Speed Sensor, Speed Present Despite Rear PTO Being Switched Off

Triggered when the control software still registers a speed signal from the rear Power Take-Off (PTO) speed sender (Sensor B06) for too long (typically 20 seconds) after the rear PTO has been commanded off. This condition can indicate a genuine electrical/mechanical malfunction, or it can simply be triggered during the normal coasting down of a high-inertia implement after the PTO has been disengaged.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6020 Series
• 6120
• 6420
• 6120L
• 6520L
• 6030 Series
• 6230
• 6330
• 6430
• 6M Series
• J Series
• 6145J
• 6165J
• 6180J
• 6205J
• 7R Series
• 8R Series
• 9R Series

1. 1

   Verify Operational Context: Confirm whether the fault code was set under normal operational conditions (e.g., a heavy implement coasting down). If so, this may not signify a fault. Reset the code and monitor.

2. 2

   Inspect Rear PTO Speed Sensor (B06): Check the sensor and its wiring harness for any signs of damage, wear, shorts, or disconnections that might cause erroneous readings.

3. 3

   Test Sensor Accuracy: Use the tractor's onboard diagnostic mode (e.g., CCU Diagnostic Mode Address 4 on older models) or a service tool to test the PTO speed sensor's accuracy. Verify that the sensor consistently changes states (0-1-0-1) when turned by hand and stops sending data when the PTO is genuinely off.

4. 4

   Check the Rear PTO Solenoid Valve (Y04): Test for a mechanical defect (valve stuck open) or an electrical short-circuit keeping the valve energized.

5. 5

   Check the PTO Modulating Valve: Inspect for defects that could allow hydraulic pressure to bypass and keep the PTO clutch engaged.

1. 1

   Clear and Retest

   If the code was caused by implement coast-down, clear the diagnostic code from the BCU/RPT and perform a test run to see if it returns.

2. 2

   Resolve Wiring Issues

   If the B06 sensor wiring is chafed or shorted, repair the harness and ensure the sensor is securely mounted.

3. 3

   Replace the Speed Sensor

   If diagnostics confirm the B06 sensor is malfunctioning and sending phantom speed data when the shaft is stationary, remove and replace the Rear PTO Speed Sensor.

4. 4

   Replace the PTO Solenoid Valve

   If the sensor is reading correctly but the PTO shaft is actually continuing to spin because the clutch won't disengage, replace the Rear PTO Solenoid Valve (Y04) or the PTO Modulating Valve.

5. 5

   System Check

   After replacing the faulty component, reset the control unit to clear the codes and perform a comprehensive system check to ensure the PTO engages and disengages within the specified time limits.