Case IH 15260 - AST – AST (Advanced Steering / Steering Controller): Cut-off solenoid stuck open. Spool movement test at transition from on-road to off-road failed.

The system has detected that the cut-off solenoid located on the steering valve is mechanically or electrically stuck in the open position. The Advanced Steering (AST) system runs a spool movement self-test when the operator transitions the machine from on-road (transport) mode to off-road (field) mode. When the spool fails to move as commanded because the solenoid is stuck open, this code is triggered.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Puma Series
• Case IH Maxxum Series
• Case IH Optum Series
• Case IH Steiger / Quadtrac Series
• Case IH Farmall C Series (Tier 5/Stage V)

1. 1

   Attempt to perform an AST Steering Calibration using the tractor's instrument cluster (H Menu) or the Electronic Service Tool (EST)

2. 2

   Inspect the wiring harness leading to the steering valve's cut-off solenoid for chafing, corrosion, or a short-to-ground that might be keeping the solenoid energized (open)

3. 3

   Use a multimeter to ohm-test the cut-off solenoid coil to ensure it is within the manufacturer's specified resistance range and not internally shorted

4. 4

   Check the hydraulic filters and fluid condition for contamination or debris that could cause the spool valve to physically bind

1. 1

   Depressurize the System

   Ensure the tractor is parked on a level surface, the engine is off, and the hydraulic pressure is fully relieved by cycling the steering wheel and remotes.

2. 2

   Locate the Steering Valve

   Access the main steering valve block (usually located under the cab or near the front axle depending on the model).

3. 3

   Remove the Solenoid

   Disconnect the electrical harness from the cut-off solenoid. Unthread the solenoid cartridge from the steering valve body.

4. 4

   Inspect the Spool and Cavity

   Check the valve cavity for metal shavings, debris, or scoring. Clean the cavity with a lint-free cloth and hydraulic-safe solvent if necessary.

5. 5

   Replace the Solenoid

   If the solenoid is mechanically stuck or electrically failed, install a new cut-off solenoid cartridge. Lubricate the O-rings on the new solenoid with clean hydraulic fluid before threading it in.

6. 6

   Reassemble and Reconnect

   Torque the solenoid to OEM specifications and reconnect the electrical harness.

7. 7

   Calibrate and Test

   Start the tractor, check for leaks, and use the EST or H Menu to clear the 15260 fault code. Perform the AST Steering Calibration and test the transition from on-road to off-road mode to ensure the spool movement test passes.