Case IH P36 – Electronic Management Unit (EMU): Rear PTO Failure To Start - Relay Or Switch Wiring Fault

The electronic management system has detected an open circuit, short circuit, or communication failure in the wiring harness, the rear PTO switch, or the PTO relay, preventing the rear Power Take-Off (PTO) from engaging.

• MXM
• MXM Series 120
• MXM Series 130
• MXM Series 140
• MXM Series 155
• MXM Series 175
• MXM Series 190
• CVX Series 140
• CVX Series 150
• CVX Series 160
• CVX Series 170
• CVX Series 175
• CVX Series 195
• CVX Series 1135
• CVX Series 1145
• CVX Series 1155
• CVX Series 1170
• CVX Series 1190
• CVX Series 1195
• CS Series 80
• CS Series 85
• CS Series 90
• CS Series 95
• CS Series 100
• CS Series 105
• CS Series 150
• Maxxum Series
• Farmall Series
• Puma Series
• MX/TG Series

1. 1

   Perform a battery reset by disconnecting the tractor's battery for a short period to reset the electronic control systems and clear any transient errors.

2. 2

   Remove the rear PTO switch from the right-hand console, disconnect the connector, and inspect each terminal and wire connection for corrosion, pushed-out pins, or damage.

3. 3

   Ensure the connector is refitted securely, turn the key on, and check if error code P36 still shows.

4. 4

   If the code persists, substitute the switch with a known good unit to see if the fault clears.

5. 5

   If the engine cranks but will not start (symptom-specific): remove the floor mat and floor plate to access and check the large 48-pin round connectors for loose pins, moisture, or poor connections.

1. 1

   Power Down

   Turn off the tractor and disconnect the negative battery terminal.

2. 2

   Access the Switch

   Carefully pry or unscrew the rear PTO switch from the right-hand operator console.

3. 3

   Wiring Repair

   If the diagnostic inspection revealed damaged wiring or a faulty connector at the switch, repair or replace the wiring harness pigtail as required.

4. 4

   Replace the Switch/Relay

   If the wiring is intact, replace the faulty rear PTO switch or the PTO relay module.

5. 5

   Reassembly

   Plug the new switch/relay into the harness, ensuring the locking tab clicks into place. Reinstall the switch into the console.

6. 6

   Test

   Reconnect the battery, start the tractor, and engage the rear PTO to verify the P36 code is permanently corrected and the PTO operates smoothly.