Case IH 120 – TMF (Tractor Multi-Function) Controller / ATC (Armrest Tractor Controller): Electro Hydraulic Remote top link switch is stuck on.

The control module is receiving a continuous, uninterrupted 'ON' signal from the external fender-mounted switch used to extend or retract the hydraulic top link. This condition is typically caused by a physically jammed switch button (due to dirt, debris, or damage), an internal electrical short within the switch, or a short-to-power (12V) in the wiring harness.

• Magnum
• MX Magnum
• Magnum 215-305
• Magnum 235-340
• Magnum 250-380
• Steiger 435
• Steiger 500
• Steiger 550
• TG Series
• CVX Series

1. 1

   Visual & Physical Inspection: Inspect the top link switch located on the rear fender. Check if the button is physically stuck, depressed, or packed with mud, ice, or debris. Clean the area thoroughly.

2. 2

   Disconnect Test: Unplug the electrical connector from the back of the fender switch. If Fault Code 120 goes inactive (or changes to an 'open circuit' code), the switch is internally shorted and must be replaced.

3. 3

   Disconnect Test (continued): If the code remains active while the switch is unplugged, the switch is not the problem. You have a short-to-power (12 Volts) in the wiring harness between the switch connector and the TMF/ATC controller.

4. 4

   Harness Inspection: Inspect the wiring harness leading from the fender down to the main chassis for chafing, pinched wires, or melted insulation that could cause a short to a 12V source.

5. 5

   Connector Check: Check the switch connector for water ingress or heavy corrosion, which can bridge the terminals and cause a false 'on' signal.

1. 1

   Power down tractor

   Turn off the tractor and remove the key to ensure the TMF/ATC modules are powered down.

2. 2

   Locate switch

   Locate the faulty Electro Hydraulic Remote top link switch on the rear fender.

3. 3

   Disconnect harness

   Reach behind the fender panel and depress the locking tab to disconnect the electrical harness plug from the switch.

4. 4

   Remove retaining hardware

   Remove the retaining nut or locking tabs securing the switch to the fender housing.

5. 5

   Remove old switch

   Push the old switch out of the fender mounting hole.

6. 6

   Install new switch

   Insert the new OEM switch into the fender receptacle and secure it with the retaining nut/clips.

7. 7

   Reconnect harness

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

8. 8

   Test switch

   Turn the tractor key to the ON position, clear the inactive fault codes from the display, and test the fender switch to ensure the hydraulic top link extends and retracts properly without throwing a new code.