New Holland TMF 174 – TMF Controller: Current flowing in the PTO sense resistor when the high side is off.

The controller is detecting electrical current flowing through the Power Take-Off (PTO) solenoid circuit's sense resistor even though the high-side driver (the internal switch supplying power to the circuit) is commanded OFF. This indicates an electrical fault where the circuit is receiving power from an unintended source (a short to power), a faulty PTO solenoid, or an internal failure within the controller itself.

• TG215
• TG245
• TG275
• TG305
• T8010
• T8020
• T8030
• T8040
• T9 Series
• T9000 Series
• MX Magnum
• TG series

1. 1

   Inspect the wiring harness between the TMF controller and the PTO solenoid for chafed wires, melted insulation, or pinched harnesses that could cause a short to a 12V power source.

2. 2

   Disconnect the PTO solenoid connector and the TMF controller connector to check for corrosion, bent pins, or moisture ingress.

3. 3

   Test the PTO solenoid for internal shorts using a multimeter.

4. 4

   With the PTO commanded OFF, check if voltage is still present at the solenoid connector pins. If voltage is present while the harness is isolated, the TMF controller may have an internal short.

1. 1

   Isolate the Battery

   Turn off the machine and disconnect the battery to prevent electrical spikes during repair.

2. 2

   Repair Wiring

   If the diagnostic checks reveal a short to power in the wiring harness, repair the damaged section of the wire or replace the PTO solenoid wire assembly.

3. 3

   Replace the Solenoid

   If the wiring is intact but the PTO solenoid fails a resistance test or is internally shorted, remove the faulty PTO solenoid valve from the PTO housing and install a new OEM replacement.

4. 4

   Replace the TMF Controller

   If both the wiring harness and the PTO solenoid test perfectly, the fault lies within the TMF controller's internal circuitry (the high-side driver has failed closed). Replace the TMF controller.

5. 5

   Clear and Calibrate

   Reconnect the battery. Clear the TMF 174 error code from the system using a diagnostic tool. Test the PTO system for normal operation to ensure the code does not return.