John Deere 186.05 – PTF: Front PTO Speed Sensor, Open Circuit

This diagnostic trouble code is triggered when the control software registers that the voltage at the output of the front PTO speed sensor is too high, which indicates an open circuit. An open circuit means there is a physical break, disconnection, or severe corrosion in the electrical pathway, preventing the sensor from communicating the PTO shaft's RPM to the tractor's computer.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6100MC
• 5070M
• 5080M
• 5080R
• 5100R

1. 1

   Inspect Sensor Wiring: Trace the wiring harness leading to the front PTO speed sensor. Look for any signs of chafing, broken wires, or disconnected lines that would cause an open circuit.

2. 2

   Verify Sensor Connections: Ensure the electrical connector at the sensor is securely seated. Disconnect it and inspect the pins for dirt, moisture, or corrosion.

3. 3

   Test Sensor and Circuit: Use a multimeter to test the front PTO speed sensor and its associated circuit for continuity.

4. 4

   Check Control Software: Verify that the tractor's control software is updated to the latest version, as software patches sometimes address false open-circuit voltage readings.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery to prevent any electrical damage during the repair.

2. 2

   Locate the Sensor

   Locate the Front PTO speed sensor, which is mounted near the front PTO shaft/clutch assembly.

3. 3

   Clean and Reconnect

   If the diagnostic checks revealed a loose or dirty connector, clean the pins with electrical contact cleaner, apply dielectric grease, and reconnect it securely. Reconnect the battery and check if the code clears.

4. 4

   Repair Wiring

   If a break in the wiring harness was found, splice and seal the damaged wires using weather-sealed connectors.

5. 5

   Replace the Sensor

   If the wiring is intact but the sensor failed the continuity test, remove the mounting bolt(s) holding the faulty sensor and pull it out.

6. 6

   Install New Sensor

   Insert the new PTO speed sensor. Ensure it sits at the correct gap from the tone ring (if adjustable on your specific model) so it can accurately read the RPMs.

7. 7

   Verify Operation

   Reconnect the battery, clear the fault codes from the monitor, and start the tractor. Engage the front PTO and verify that the display shows steady RPM readings without the code returning.