Case IH 172 – TMF (Tractor Multi-Function) Controller: PTO Solenoid Circuit is failed shorted to 12 Volts when PTO is in the off state.

The controller is detecting voltage on the Power Take-Off (PTO) solenoid circuit when the system is commanded to be de-energized (off). The underlying condition is typically caused by the wiring harness shorted to a 12-volt power source, the PTO solenoid coil failing internally, or the controller itself failing.

• Magnum
• Case IH MX Magnum Series
• Case IH TG Series
• Case IH Maxxum Series
• Case IH Puma Series

1. 1

   Turn the tractor off and remove the cover at the rear of the tractor to access the TMF controller.

2. 2

   Disconnect the PTO controller connector (C057) and test the resistance of the PTO solenoid circuit directly through the harness.

3. 3

   If the resistance is out of specification (too low), disconnect the harness directly at the PTO solenoid valve and test the coil's resistance to check for an internal short.

4. 4

   If the solenoid tests good, use a multimeter to check the wiring harness between the TMF controller and the solenoid for continuity to a 12V power source.

5. 5

   If the wiring and solenoid are both good, check the output pins on the TMF controller. If it outputs 12V to the PTO circuit while the PTO switch is OFF, the controller has failed.

1. 1

   Ensure Safety

   Park the machine on a level surface, turn off the engine, and remove the key.

2. 2

   Address Wiring (If Applicable)

   If a short to 12V was found in the harness during diagnostics, trace the harness to locate the chafed or melted wires. Splice and repair the damaged section using weather-sealed connectors, or replace the affected harness section.

3. 3

   Replace the PTO Solenoid (If Applicable)

   Clean the area around the PTO solenoid valve on the transmission/rear housing to prevent dirt ingress. Disconnect the electrical connector from the solenoid. Unthread the retaining nut or mounting bolts holding the solenoid coil/valve in place. Install the new PTO solenoid valve, ensuring O-rings are lubricated with clean hydraulic fluid. Torque to OEM specifications and reconnect the harness.

4. 4

   Replace the TMF Controller (If Applicable)

   If the controller's internal relay is stuck on, disconnect the battery, remove the faulty TMF module, and install a replacement or remanufactured unit. Note: A new TMF controller may require dealer calibration using the Case IH Electronic Service Tool (EST).

5. 5

   Verify Repair

   Reconnect the battery, clear the stored fault codes, and cycle the PTO switch to ensure normal operation without the code returning.