New Holland 3734 – EDC: PTO switch : Diagnostic fault check non plausibility of COM message.

This code indicates that the control module is receiving an implausible signal or CAN (Controller Area Network) message regarding the state of the Power Take-Off (PTO) multi-state switch. The sensed raw voltage or signal value from the PTO switch is falling outside the expected calibrated thresholds (either below the minimum or above the maximum threshold), or there is a communication error or loss of synchronization over the CAN bus regarding the switch's position.

• TS Series
• TS90
• TS100
• TS110
• TS115
• TM Series
• TM115
• TM165
• TM190
• TL Series
• TN Series
• T6 Series
• T7 Series
• 40 Series
• Maxxum
• Puma
• MXM Series

1. 1

   Connect the CNH E.A.S.Y. (Electronic Service Tool) diagnostic tool and monitor live data for the PTO switch state to see if the ECU registers the state change or if it reads as implausible or out of range.

2. 2

   Inspect the physical PTO switch on the cab console for sticking, mechanical damage, or liquid intrusion (a common cause of switch failure in open-cab or heavily washed tractors).

3. 3

   Disconnect the PTO switch and inspect the connector pins for corrosion, pushed-out pins, or moisture.

4. 4

   Using a multimeter, check the wiring harness between the PTO switch and the ECU for continuity, short-to-ground, or short-to-power.

5. 5

   Verify the CAN bus network integrity if the switch and direct wiring test good, as this is a COM message error.

1. 1

   Power down

   Turn off the tractor, remove the key, and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Access the switch

   Carefully pry up or unscrew the side console/dash panel housing the PTO switch to gain access to the rear of the switch.

3. 3

   Disconnect harness

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

4. 4

   Remove the switch

   Depress the retaining tabs on the sides of the switch body and push it upward/outward through the console panel.

5. 5

   Install new part

   Snap the new OEM PTO switch into the console panel until the retaining tabs click into place.

6. 6

   Reconnect harness

   Plug the electrical harness back into the switch, ensuring the locking tab engages securely.

7. 7

   Reassemble and power up

   Reinstall the console panel and reconnect the battery.

8. 8

   Clear codes and test

   Connect the diagnostic tool, clear the inactive 3734 fault code, and run the tractor. Engage and disengage the PTO to verify proper operation and ensure the code does not return.