Case IH P33 – Electronic Management Unit (EMU) / PTO Controller: Rear PTO Cab Switch Momentary Contact Open (or Open Circuit)

This code indicates that the electronic control system has detected an open circuit in the momentary contact circuit of the rear Power Take-Off (PTO) switch located in the tractor's cab.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190
• Maxxum
• MXU
• Puma
• CVX
• CS
• Farmall
• MX

1. 1

   Check the rear PTO switch resistance across the momentary contact pins (blue and black wires) for a reading of 15 kΩ

2. 2

   Inspect the wiring harness connected to the momentary contacts of the PTO switch for visible damage or chafing

3. 3

   Perform a continuity test between touch panel connector C105 (pin 13) and PTO controller connector C116 on wire 2048 O/Y (Orange/Yellow) to check for an open circuit

1. 1

   Disconnect the Battery

   Disconnect the tractor's battery for a short period. This ensures safety during electrical work and may help reset the electronic control systems.

2. 2

   Access the Switch

   Carefully pry or unscrew the right-hand console panel to access the rear PTO cab switch wiring and retaining clips.

3. 3

   Test/Replace the Switch

   Perform the 15 kΩ resistance test. If the switch is open or out of specification, unclip the harness, remove the old switch, and snap the new OEM switch into the console.

4. 4

   Repair Wiring (If Applicable)

   If the switch is good, trace the 2048 O/Y wire between connectors C105 and C116. Locate the break or chafe in the harness and repair it using proper automotive-grade wire splicing and heat shrink.

5. 5

   Reassembly

   Reconnect all harness connectors (C105, C116) and reinstall the right-hand console panel.

6. 6

   Test Operation

   Reconnect the battery and turn the ignition on. Engage the rear PTO to verify operation. If the code persists, a certified mechanic may need to clear the DTC using a CNH diagnostic tool.