New Holland TMF 173 – TMF: PTO Solenoid Circuit is failed shorted to ground when PTO is in the off state

The control module is detecting an electrical path to ground on the Power Take-Off (PTO) solenoid control circuit while the PTO switch is turned off. This condition can prevent the PTO from engaging properly or cause erratic behavior, as the circuit is grounding out before the electrical current can properly energize the solenoid coil.

• T6
• T7
• T8
• T9
• TG
• TM
• MXM
• TD5
• TS
• CR
• CR9090
• CX
• CX8080
• CX8090
• Magnum
• Steiger
• Farmall

1. 1

   Visually inspect the PTO solenoid wiring harness routing along the transmission housing and chassis for rubbed, chafed, or melted wires touching the metal frame (causing the short to ground).

2. 2

   Disconnect the electrical connector at the PTO solenoid and use a multimeter to measure resistance between the power supply wire in the harness and a known good chassis ground. Continuity indicates a shorted harness.

3. 3

   If the harness tests fine, measure the resistance across the PTO solenoid coil pins, and from the pins to the solenoid's metal casing to check for an internal short.

4. 4

   Inspect the multi-pin connectors at the TMF controller for moisture, corrosion, or bent pins that could be bridging circuits.

1. 1

   Park the machine on a level surface, turn off the engine, and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Locate the PTO solenoid valve, which is typically positioned on the rear transmission housing or the independent PTO control hydraulic manifold.

3. 3

   Disconnect the wiring harness connector from the PTO solenoid.

4. 4

   If the diagnostic checks revealed a wiring issue, splice and repair the chafed wire using heat-shrink connectors, or replace the damaged section of the PTO wire harness.

5. 5

   If the solenoid is internally shorted, remove the retaining nut or bolt holding the solenoid coil to the hydraulic valve stem.

6. 6

   Slide the old solenoid off and install the replacement OEM solenoid.

   Note: On some models, the entire control valve cylinder must be replaced rather than just the coil.

7. 7

   Reconnect the electrical harness to the new solenoid.

8. 8

   Reconnect the battery.

9. 9

   Turn the key on, clear the inactive fault codes via the tractor's instrument cluster or a diagnostic service tool, and test the PTO engagement to ensure the code does not return.