Massey Ferguson T146 – TRANS1: PTO Switch Is On But The PTO Is Not Turning Dyna 6 (TRANS1)

The operator has engaged the PTO switch in the cab, but the tractor's computer is receiving a 0 RPM signal from the PTO speed sensor. The system recognizes a mismatch between the commanded state (PTO ON) and the physical state (PTO shaft not rotating).

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 6613
• 6614
• 6615
• 6616
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Perform a PTO speed sensor resistance test (should read 450 Ohms +/- 20 Ohms at room temperature).

2. 2

   Inspect the wiring harness between the PTO speed sensor and the TRANS1 module for chafed wires, broken connections, or corrosion.

3. 3

   Check the transmission control solenoid (electrovalve) to verify it receives a 12V signal when the PTO switch is activated.

4. 4

   Perform a hydraulic pressure test at the PTO clutch test port to ensure hydraulic pressure reaches the clutch pack.

1. 1

   Verify the Sensor

   If the PTO speed sensor fails the resistance test (reads open circuit or significantly out of the 450-ohm range), it has failed internally. Clean the area around the mounting port, unbolt the old sensor, and install a new OEM speed sensor.

2. 2

   Test/Replace the Solenoid

   If the sensor is reading correctly but the PTO still physically isn't turning, test the PTO engagement electrovalve/solenoid. If the coil is burnt out or the valve is stuck closed, relieve the hydraulic pressure, remove the retaining hardware on the valve block, and replace the solenoid.

3. 3

   Mechanical Teardown (Worst Case)

   If the speed sensor, wiring, solenoid, and hydraulic pressures are all functioning perfectly, the fault lies within the mechanical driveline. Drain the hydraulic fluid and remove the rear PTO housing to rebuild the clutch pack.

4. 4

   Clear Codes

   After replacing any electrical components, use a diagnostic tool to clear the T146 code from the TRANS1 module and test the PTO under load to ensure the RPM readout is accurate.