Case IH P37 – Electronic Management Unit (EMU): Rear PTO Cab Switch Momentary Contact is Stuck Closed (Longer Than 30 Seconds) OR has an Open Circuit

The system detects that the in-cab Power Take-Off (PTO) engagement switch is either physically/internally stuck in the engaged position for an abnormal amount of time, or the electrical circuit connecting the switch to the control module has been broken (open circuit).

• MXM
• MXM Series (MXM 120, 130, 140, 155, 175, 190)
• Puma Series
• Maxxum / MXU Series
• Farmall Series (75C, 85C, 105U, 115U)
• Luxxum Series
• Magnum / MX / TG Series

1. 1

   Press the rear PTO cab switch to see if it feels physically jammed, sticky, or fails to spring back to its neutral position.

2. 2

   Remove the switch and use a multimeter to test for continuity. Verify that the momentary contacts close when pressed and immediately open when released. If they remain closed, the switch is internally shorted/stuck.

3. 3

   If the switch operates correctly, use a multimeter to check the wiring harness between the cab switch connector and the Electronic Management Unit (EMU). Look for an open circuit (broken wire) or a short to ground.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical shorts during repair.

2. 2

   Access the Switch

   Carefully pry up or unscrew the right-hand B-pillar console or side console trim panel where the rear PTO switch is mounted.

3. 3

   Disconnect

   Unplug the wiring harness connector from the back of the PTO switch.

4. 4

   Remove and Replace

   Depress the retaining tabs on the sides of the switch body to pop it out of the console panel. Insert the new OEM replacement switch until it clicks into place.

5. 5

   Wiring Repair (If applicable)

   If the switch was tested and found to be functional, locate the break in the wiring harness traced during your diagnostic checks. Splice and heat-shrink the broken wire, or replace the damaged harness section.

6. 6

   Reassembly

   Reconnect the wiring harness to the new switch, reinstall the console trim panel, and reconnect the battery.

7. 7

   Clear and Test

   Turn the key on, clear the inactive fault codes from the EMU/Instrument cluster, and test the PTO engagement to ensure P37 does not return.