Case IH 5025 – Tractor Control Unit (TCU): Rear PTO / PTO low side driver watchdog test failed

The control module has detected an electrical fault, wiring irregularity, or software logic error on the low-side driver circuit that monitors and controls the Rear Power Take-Off (PTO) solenoid.

• Magnum
• Steiger
• Puma
• Maxxum

1. 1

   Check the Tractor Control Unit (TCU) wiring harness for any recent repairs, rubbing, or damage

2. 2

   Locate TCU connector C063 and check the status of Pin 8 (watchdog test often fails if this pin is incorrectly wired or shorted to ground)

3. 3

   Verify if the issue is software-related, as OEM bulletins note this code can be triggered by a software logic error rather than a physical failure

1. 1

   Access the TCU

   Locate the Tractor Control Unit and disconnect the battery to ensure safety before probing the harness.

2. 2

   Inspect Connector C063

   Disconnect TCU connector C063.

3. 3

   Verify Pin 8

   Inspect pin 8 on connector C063. If any recent harness repairs were made, ensure that pin 8 is open (not incorrectly pinned or shorted), as an improper connection here will cause the low-side driver watchdog test to fail.

4. 4

   Correct the Wiring

   If pin 8 was incorrectly wired, depin or correct the wiring to leave it open as per the factory schematic.

5. 5

   Reconnect and Clear Codes

   Reconnect connector C063, restore battery power, and use the Electronic Service Tool to clear fault code 5025.

6. 6

   Field Test

   Engage the Rear PTO to verify the code does not return.

7. 7

   Software Update (If Applicable)

   If the wiring at C063 is completely factory-correct and the code persists, connect the Electronic Service Tool and flash the TCU with the latest software version to resolve potential logic errors.