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

The controller is receiving conflicting electrical signals (both "raise" and "lower" commands at the exact same time) or an invalid voltage from the rear fender hitch switch circuit. This is most commonly caused by a physically stuck button, water intrusion causing an internal short in the switch, or a short circuit in the wiring harness.

• Magnum
• MX Magnum
• Steiger
• STX
• Puma
• Maxxum
• CVX
• MX

1. 1

   Visually inspect the rear fender hitch switches for physical damage, packed dirt, or debris that might be holding both the UP and DOWN buttons down simultaneously.

2. 2

   Press the buttons manually to see if they are physically stuck or lack their normal spring return.

3. 3

   Disconnect the wiring harness from the back of the fender switch and inspect the pins for corrosion, rust, or moisture ingress.

4. 4

   Inspect the wiring harness running from the fender to the cab for chafing, pinched wires, or exposed copper that could be shorting the UP and DOWN signal wires together or to a ground/power source.

5. 5

   Test the switch itself with a multimeter to ensure that it does not show continuity for both the UP and DOWN circuits at the same time when the switch is at rest.

1. 1

   Power Down

   Turn off the tractor key and disconnect the battery to prevent electrical spikes to the TMF controller.

2. 2

   Access the Switch

   Locate the faulty switch on the rear fender housing.

3. 3

   Disconnect

   Reach behind the fender (or remove the protective cover panel, depending on the model) and unplug the electrical connector from the switch.

4. 4

   Remove the Switch

   Depress the retaining tabs or remove the mounting screws securing the switch to the fender, and push the old switch out of its mounting hole.

5. 5

   Install the New Part

   Snap or screw the new OEM switch into the fender housing.

6. 6

   Reconnect

   Apply a small amount of dielectric grease to the electrical connector to prevent future moisture intrusion, and plug the harness back into the switch.

7. 7

   Clear Codes and Test

   Reconnect the battery, turn the ignition on, and clear the stored fault codes from the TMF controller. Test the 3-point hitch operation using both the cab controls and the new fender switch to verify the repair.