John Deere 000186.17 – BCU or CCU: Rear PTO Speed Too Slow on Rear Chassis

The rear Power Take-Off (PTO) speed is below the expected threshold while the PTO is engaged. The tractor's control unit detects that the PTO shaft is rotating too slowly or not at all when it should be operating at a specific RPM. This triggers the fault code and, in many cases, will cause the control unit to disengage the PTO to prevent damage to the clutch or attached implements.

• 6230
• 6330
• 6420
• 6430
• 7410
• 7520
• 7600
• 7700
• 7710
• 7800
• 7810
• 8410

1. 1

   Perform an initial reset by switching the PTO off and then on again to clear temporary glitches

2. 2

   Carefully inspect the wiring harness and connectors leading to the PTO speed sensor and the PTO control solenoid for any signs of damage, corrosion, or loose connections

3. 3

   Check for other diagnostic trouble codes that may indicate a related issue in another tractor sub-assembly

4. 4

   Ensure the operator presence switch in the seat is functioning correctly, as this is a common interlock for PTO operation

5. 5

   Verify the functionality of the PTO engagement switch in the cab

6. 6

   Retrieve detailed codes from the CCU/BCU (e.g., by placing a fuse in the DIAG position and using the turn signal lever) to test the speed sensor and switch circuits

1. 1

   Test the PTO speed sensor

   Locate the sensor on the rear transmission or PTO housing (e.g., above the rear axle on a 6420). Turn the PTO shaft by hand and observe the signal in the diagnostic menu; it should consistently alternate. Check sensor resistance with a multimeter; expect approximately 3000 Ohms. A zero reading indicates a bad sensor.

2. 2

   Inspect the tone wheel

   With the speed sensor removed, visually inspect the tone wheel (the toothed wheel the sensor reads) for damage or looseness on the shaft.

3. 3

   Test the PTO solenoid

   Locate the PTO solenoid on the control valve at the rear of the tractor. Swap the PTO solenoid coil with an identical one from another function (like differential lock or MFWD). If the PTO works and the other function fails, replace the faulty solenoid coil.

4. 4

   Check PTO clutch and mechanical components

   If electrical components test correctly, the issue may be internal to the PTO clutch pack, such as worn clutch plates or internal hydraulic pressure issues. This is a more involved repair that may require a qualified technician.