Massey Ferguson 6.X.4D – Rear PTO Management System / PTO Controller: X776 - Rear PTO end-fitting: The number of splines on the speed sensor PTO output shaft is undetermined.

The inductive speed sensor (X776) cannot identify the installed interchangeable PTO stub shaft, leaving the tractor's computer unable to determine the correct PTO speed configuration.

• 5710SL
• 5711SL
• 5712SL
• 5713SL
• T4
• MF 4700 Series
• 4707
• 4708
• 4709
• 4710
• MF 5700 Series
• MF 6700 Series
• 6713

1. 1

   Inspect the Stub Shaft Flange: Check if any dirt, mud, or debris is trapped between the PTO stub shaft mounting surfaces preventing the shaft from seating fully.

2. 2

   Check the X776 Sensor: Locate the X776 inductive speed sensor at the rear PTO housing and inspect it for heavy dirt buildup, moisture ingress, or physical damage.

3. 3

   Wiring and Connector Inspection: Check the wiring harness and the connector for the X776 sensor for corrosion, loose pins, or broken wires that would interrupt the signal.

4. 4

   Verify the Shaft: Ensure the installed stub shaft is an OEM-spec part and that the center pin/target is functioning properly and not seized.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, and disconnect the battery to protect the electronic systems.

2. 2

   Remove the Stub Shaft

   Remove the 4 bolts holding the PTO stub shaft to the rear housing and pull the shaft out.

3. 3

   Clean the Housing

   Thoroughly clean the mounting flange and the internal area where the X776 sensor reads the shaft.

4. 4

   Replace the Sensor (if faulty)

   If diagnostics point to a failed sensor, locate the X776 sensor on the housing. Remove its retaining hardware and carefully pull the old sensor out (access can be tight near the PTO shaft).

5. 5

   Install the New Sensor

   Insert the new inductive speed sensor and secure it. Reconnect the wiring harness, ensuring the connector clicks into place and is sealed against moisture.

6. 6

   Reinstall the Stub Shaft

   Insert the correct PTO stub shaft (540 or 1000 RPM). Ensure it sits completely flush against the housing with no gaps.

7. 7

   Torque Bolts

   Reinstall the 4 retaining bolts and tighten them to the manufacturer's specified torque.

8. 8

   Test

   Reconnect the battery, start the tractor, and engage the PTO. Verify that the cab display reads the correct RPM and that the 6.X.4D fault code has cleared.