New Holland 174 – TMF: PTO Sense Resistor Current Detected

The Transmission/Main Frame (TMF) controller has detected electrical current in the Power Take-Off (PTO) sensor circuit when the circuit is supposed to be de-energized (high side off). This indicates an unexpected electrical path, such as a short circuit or a faulty component in the circuit associated with the PTO sense resistor.

• TM120
• TM130
• TM140
• TM155
• TM175
• TM190

1. 1

   Check for any other active fault codes, as issues with other sensors or circuits can sometimes trigger related codes

2. 2

   Ensure that all related fuses are intact and that the main ground connections to the chassis are clean and secure

3. 3

   Inspect the wiring harness leading to the PTO switch, PTO solenoid, and any related sensors for visible signs of damage, such as chafing, corrosion, or pinched wires

4. 4

   Test the functionality of the fender-mounted and in-cab PTO switches to ensure they are not stuck

5. 5

   Disconnect and inspect the electrical connectors for the PTO circuit components, looking for bent, loose, or corroded pins, as well as signs of water or oil intrusion

1. 1

   Isolate the fault

   Begin by disconnecting components of the PTO circuit one by one to see if the fault code clears. This can help pinpoint the source of the unexpected current.

2. 2

   Test the PTO solenoid

   Test the solenoid's resistance and check for a short to ground. A shorted solenoid coil can cause current to flow when it shouldn't.

3. 3

   Test the PTO switch

   Disconnect the PTO switch and test its continuity. It should only show continuity when activated. If it is stuck in a closed position, replace the switch.

4. 4

   Trace the wiring

   Using a wiring diagram for the specific tractor model, trace the wires for the PTO sense circuit. Check for continuity and shorts between wires and to the chassis ground. Repair any damaged sections of the harness.

5. 5

   Check the sense resistor

   If the wiring, switch, and solenoid are in good condition, test the sense resistor's resistance value against the specifications in the service manual. Its location may vary and it might be part of a larger component or wiring loom.

6. 6

   Replace the TMF controller

   If all other components and wiring have been ruled out, the TMF controller itself could be the source of the problem. This is the least likely cause and should be considered a last resort.