Case IH 5026 – Tractor Control Unit (TCU) or PTO Controller: The 12 volt supply to the PTO is too low

The controller monitoring the Power Take-Off (PTO) circuit has detected that the voltage supplying the PTO solenoid or related circuitry has dropped below the acceptable operating threshold (typically below 11.0 V).

• Steiger T4B
• Case IH Magnum Series (235-340 Series 4)
• Case IH Magnum MX210
• Case IH Magnum MX230
• Case IH Magnum MX255
• Case IH Magnum MX285
• Case IH STX Steiger Tractors

1. 1

   Check overall battery/system voltage using the tractor's cab display monitor with the engine running

2. 2

   Check the fuse panel for a blown fuse on the 12VS2 (PTO 12V supply) circuit

3. 3

   Inspect for bad connections, corrosion, or backed-out pins at the Tractor Control Unit (TCU) harness and the PTO solenoid connector

1. 1

   Evaluate Voltage

   Start the tractor and read the battery voltage on the display. If the battery voltage is below 11.0 V, test the battery and the alternator/alternator regulator, and repair or replace the charging system components as necessary. If the battery voltage is normal (12.0 V - 14.0 V), the issue is isolated to the PTO circuit.

2. 2

   Check the Fuse

   Locate the fuse associated with the PTO 12V supply (12VS2). If it is blown, replace it. If it blows again immediately upon PTO engagement, there is a short to ground in the harness or the solenoid.

3. 3

   Inspect the Wiring Harness

   Trace the wiring harness from the TCU to the PTO solenoid. Look for chewed wires, chafing, or damaged connectors (a common issue on the rear cab harness near the draft arm cross tube).

4. 4

   Test the Solenoid

   If the wiring is intact, test the resistance of the PTO solenoid to ensure it hasn't failed open or shorted out.

5. 5

   Clear and Retest

   Once repairs are made (or if a loose connection was re-seated), clear the fault code from the display, shut down the engine, restart, and engage the PTO to verify the code does not return.