New Holland TMF 26 – TMF (Tractor Multi-Function) Controller: Fender UP and DOWN switch failure or both switches simultaneously pressed

The controller is receiving an invalid signal from the external rear fender hitch control switches. The system triggers this code either because the operator physically pressed the raise and lower buttons at the exact same time, or because there is an electrical failure (such as an internal short in the switch or a wiring harness short) causing both circuits to show as active simultaneously.

• T4
• T5
• T6
• T7
• T8000 series
• T8010
• T8020
• T8030
• T8040
• TG210
• TG230
• TG255
• TG285
• TM Series
• TS Series
• Magnum
• Maxxum
• Puma

1. 1

   Visually inspect the rear mudguard/fender hitch switches to see if either the UP or DOWN button is physically jammed, stuck in the depressed position, or packed with dirt/debris.

2. 2

   Verify that the operator did not accidentally press both the up and down buttons at the same time, which will trigger this code as a safety precaution.

3. 3

   Inspect the wiring harness leading from the fender switch to the TMF controller for chafed wires, pinched lines, or exposed copper that could be shorting to ground or shorting the UP and DOWN signal wires together.

4. 4

   Disconnect the switch and use a multimeter to test it, ensuring that continuity is only present on one circuit at a time when the respective button is pressed.

5. 5

   Check the electrical connector for water ingress or corrosion, which can bridge the connections and cause a false simultaneous signal.

1. 1

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

2. 2

   Locate the faulty hitch switch on the rear fender (mudguard).

3. 3

   Access the rear of the switch housing.

   This may require reaching under the fender or removing a small protective cover.

4. 4

   Unplug the 3-pin electrical connector from the back of the switch.

5. 5

   Remove the old switch.

   These are typically "push fit" rocker switches. Squeeze the retaining tabs on the back of the switch and push it outward through the fender panel.

6. 6

   Clean the mounting hole and the electrical connector.

   Apply dielectric grease to the connector terminals to protect against future moisture.

7. 7

   Insert the new switch into the fender cutout, pressing firmly until the retaining tabs click into place.

8. 8

   Reconnect the electrical wiring harness to the new switch.

9. 9

   Reconnect the battery, turn the ignition on, and test the fender hitch UP and DOWN functions to ensure proper operation.

10. 10

    Clear the TMF 26 fault code from the Tractor Multi-Function controller using the tractor's instrumentation panel or a diagnostic tool.