Case IH 174 – TMF (Tractor Multi-Function) Controller: Current flowing in the PTO sense resistor when the high side is off.

This code indicates that the control module is detecting electrical current on the Power Take-Off (PTO) solenoid circuit even when the PTO is commanded OFF (the high-side driver is turned off). This typically points to a short-to-power (12V) in the wiring harness between the controller and the PTO solenoid, or an internal hardware failure within the controller itself (such as a shorted internal driver).

• Magnum
• MX Magnum
• Magnum 180
• Magnum 190
• Magnum 210
• Magnum 215
• Magnum 225
• Magnum 240
• Magnum 255
• Magnum 310
• Magnum 335
• Puma 115 through 260
• Maxxum 100 through 150
• TG Series
• Optum
• Vestrum
• Farmall CVT

1. 1

   Inspect the TMF Controller connectors for moisture, corrosion, or backed-out pins

2. 2

   Check the PTO solenoid signal wire for continuity to power (12V) to identify harness shorts

3. 3

   Inspect the rear axle harness and rear PTO connectors for moisture, specifically unused connector 146M on single-speed PTO models

4. 4

   Verify alternator output and inspect the 'W' terminal (dark green wire) for erratic voltage

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent accidental shorting during testing.

2. 2

   Clean and Reseat Connections

   Locate the TMF controller. Disconnect the harness, spray the pins with electrical contact cleaner, apply dielectric grease, and securely reconnect them.

3. 3

   Test and Replace the PTO Solenoid

   Locate the PTO solenoid valve on the rear transmission/PTO housing. Test the solenoid's internal resistance. If the solenoid is internally shorted, it must be replaced.

4. 4

   Repair the Wiring Harness

   If the multimeter test (from the diagnostic steps) revealed a short-to-power in the harness, trace the wire from the PTO solenoid back to the TMF controller. Repair any chafed insulation or melted wires and re-loom the harness.

5. 5

   Install Sealing Plugs

   If you found moisture in unused rear harness connectors (like the dual-speed sensor connector on single-speed models), dry the connector thoroughly and install an OEM sealing plug to prevent future water ingress.

6. 6

   Controller Replacement/Flash

   If the wiring harness and solenoid test perfectly fine, the TMF controller has likely suffered an internal failure on the PTO sense resistor circuit. The TMF controller will need to be replaced or reflashed with a software update by a Case IH dealer.