Case IH 166 – TMF (Transmission Multi-Function) Controller or Armrest Controller: PTO Driver is on and no current is sensed

Indicates an open circuit condition. The control module has sent the electrical command to turn the Power Take-Off (PTO) solenoid ON, but the system detects zero electrical current flowing through the circuit. This is typically caused by a disconnected wire, a broken harness, corroded connector pins, or a burnt-out (open) PTO solenoid coil.

• Magnum
• MX Magnum Series
• TG Series
• Puma Series
• Puma 125
• Maxxum Series
• MX80C
• MX90C
• MX100
• MX110
• MX120
• MX135
• MX150
• MX170
• Farmall Series

1. 1

   Visually inspect the PTO solenoid valve electrical connector for unplugged connections, pushed-back pins, or heavy corrosion.

2. 2

   Trace and inspect the wiring harness from the PTO solenoid back toward the TMF/Armrest controller for chafed, pinched, or broken wires.

3. 3

   Perform a solenoid resistance test: disconnect the electrical connector and measure resistance (Ohms) across the two pins of the solenoid coil. An 'OL' (Open Loop) reading indicates a broken internal coil.

4. 4

   Perform a voltage test: with the solenoid disconnected, turn the key ON and engage the PTO switch. If 12V is present, the wiring is good and the solenoid has failed. If there is no voltage, the issue lies in the wiring harness or the controller.

1. 1

   Park the tractor on a level surface, turn off the engine, engage the parking brake, and remove the key.

2. 2

   Locate the PTO control valve block.

   Usually mounted on the rear or side of the transmission housing.

3. 3

   Disconnect the electrical wiring harness connector from the faulty PTO solenoid.

4. 4

   Clean the area around the solenoid to prevent dirt from entering the hydraulic system.

5. 5

   Remove the retaining nut or bolt at the end of the solenoid valve stem that secures the coil in place.

6. 6

   Slide the old solenoid coil off the valve cartridge.

   Note: On some models, the entire cartridge valve must be unthreaded and replaced as a single unit; have a catch pan ready for minor hydraulic fluid loss if removing the cartridge.

7. 7

   Slide the new OEM PTO solenoid coil onto the valve stem.

8. 8

   Reinstall and tighten the retaining nut/bolt to the manufacturer's specified torque.

   Do not overtighten, as this can distort the coil.

9. 9

   Reconnect the electrical harness connector, ensuring it clicks securely into place.

10. 10

    Start the tractor, engage the PTO, and verify that the PTO operates normally and fault code 166 is no longer active.