Case IH 5015 - UCM – UCM (Universal Control Module): Rear PTO fuse sense input – open circuit

The control module is not detecting the expected voltage on the PTO fuse sensing circuit. The "open circuit" designation means there is a break in the electrical path—most commonly caused by a blown fuse, a broken wire, a disconnected harness, or severe corrosion preventing current flow.

• MAXXUM T4E
• VESTRUM CVX
• Puma
• Maxxum
• Magnum
• Optum
• Axial-Flow 7230
• Axial-Flow 8230
• Axial-Flow 9230
• FR550
• FR920

1. 1

   Locate the cab fuse panel or the UCM enclosure fuse block and check if the specific fuse designated for the Rear PTO or UCM power supply is blown.

2. 2

   Using a multimeter, verify that battery voltage (12V) is present at the fuse block.

3. 3

   Disconnect the harness at the UCM and at the fuse panel. Measure the continuity of the PTO fuse sense input wire to ensure there is no break in the wire.

4. 4

   Inspect the UCM connectors and fuse board terminals for pushed-out pins, moisture, or corrosion.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the battery ground cable to prevent electrical spikes.

2. 2

   Replace the Fuse (If Applicable)

   If the diagnostic checks revealed a blown fuse, replace it with a fuse of the exact same amperage rating. (Note: If the new fuse blows immediately upon startup, there is a short to ground in the PTO wiring that must be traced and repaired before proceeding).

3. 3

   Repair the Wiring Harness

   If the fuse is intact but continuity is broken, trace the specific PTO sense wire from the fuse board to the UCM. Splice and solder any broken sections, and seal with heat-shrink tubing.

4. 4

   Clean Connections

   Apply a specialized electrical contact cleaner to the UCM harness connectors and the fuse block terminals. Reconnect the harness securely.

5. 5

   Clear the Fault Code

   Reconnect the battery and turn the key to the ON position. Enter the tractor's diagnostic "H-Menu" (or use the electronic service tool). Navigate to the UCM/PTO controller section and clear the stored error codes (often done by holding the "m" or "Decr" key until the display beeps and shows "EE" or "donE").

6. 6

   Test Operation

   Engage the Rear PTO to verify the fault code does not return and the PTO operates normally.