John Deere 186.04 – RPT (Rear Power Take-Off) Control Module: Rear PTO speed sensor, Voltage too low.

The control software detects that the voltage signal coming from the rear PTO speed sensor has dropped below the normal operating threshold, typically indicating a short to ground in the wiring, a severely corroded connector, or an internal failure of the sensor itself.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6090MC
• 6090RC
• 6100MC
• 6100RC
• 6110MC
• 6110RC

1. 1

   Inspect Sensor Wiring: Trace the wiring harness from the RPT module to the rear PTO speed sensor. Look for pinched wires, chafed insulation, or areas where the wire might be shorting to the tractor's chassis (ground).

2. 2

   Verify Sensor Connections: Disconnect the rear PTO speed sensor. Inspect the pins inside the connector for pushed-back terminals, moisture, dirt, or green corrosion.

3. 3

   Test the Circuit: Use a digital multimeter to test the sensor circuit for continuity and verify the reference voltage coming from the RPT module.

1. 1

   Power Down

   Turn off the tractor and disconnect the battery ground cable to protect the electrical system.

2. 2

   Clean/Repair Connections

   If corrosion or moisture is found in the connector, clean it thoroughly with contact cleaner and apply dielectric grease. If the connector or wiring is physically damaged, splice in a new connector pigtail or repair the broken wire.

3. 3

   Replace the Sensor

   If the wiring and voltage supply from the module test fine, the sensor itself has likely failed internally. Unbolt and remove the old rear PTO speed sensor from the PTO housing.

4. 4

   Install New Sensor

   Insert the new sensor, secure the mounting hardware, and plug in the electrical connector until it clicks.

5. 5

   Clear Codes and Test

   Reconnect the battery. Use a John Deere Service ADVISOR tool (or compatible scanner) to clear the RPT 000186.04 code. Engage the rear PTO to monitor system performance and ensure the code does not return.