New Holland TMF 166 – TMF (Tractor Multi-Function) Controller: PTO Driver is on and no current is sensed.

The control module has commanded the Power Take-Off (PTO) solenoid to turn ON, but the module's internal diagnostics detect zero electrical current flowing through the circuit. This condition almost always indicates an open circuit, commonly caused by a disconnected wiring harness, a broken wire, or a burnt-out PTO solenoid coil.

• TG210
• TG215
• TG230
• TG245
• TG255
• TG275
• TG285
• TG305
• T8010
• T8020
• T8030
• T8040
• T8050
• TM115
• TM190

1. 1

   Visually inspect the PTO solenoid valve at the rear hydraulic control block for unplugged terminals, severe corrosion, or pulled wires.

2. 2

   Perform a coil resistance test by disconnecting the harness and measuring resistance across the solenoid coil pins (an 'OL' reading indicates a broken internal coil).

3. 3

   Check the wiring harness for continuity between the PTO solenoid connector and the TMF controller pins, looking for pinch points or breaks.

4. 4

   Ensure the ground circuit for the PTO solenoid is intact and securely fastened to the chassis.

1. 1

   Prepare the machine

   Turn off the tractor, remove the key, and engage the parking brake.

2. 2

   Locate and clean the valve block

   Locate the PTO control valve block at the rear of the tractor. Clean the area around the valve to prevent dirt from entering the hydraulic system.

3. 3

   Disconnect the harness

   Disconnect the electrical harness connector from the faulty PTO solenoid.

4. 4

   Remove the retaining nut

   Remove the retaining nut located at the end of the solenoid valve stem.

5. 5

   Remove the old coil

   Slide the old solenoid coil off the valve cartridge. (Note: You usually do not need to remove the hydraulic cartridge itself, meaning no hydraulic fluid will be lost).

6. 6

   Install the new coil

   Slide the new OEM solenoid coil onto the valve stem.

7. 7

   Reinstall the retaining nut

   Reinstall and tighten the retaining nut securely (do not overtighten, as this can crack the plastic coil housing).

8. 8

   Reconnect the harness

   Apply a small amount of dielectric grease to the electrical connector pins and plug the harness back into the solenoid.

9. 9

   Verify the repair

   Start the tractor, engage the PTO switch, and verify that the PTO engages properly and that fault code TMF 166 changes to an inactive state or clears entirely.