Case IH 15255 - AST – Steering Valve Controller (SVC) / Steering Redundant Controller (SRC) / AST: Auto guidance control switch state crosscheck between the steering valve main and safety controllers failed.

The auto-guidance system uses redundant controllers (a main controller and a safety controller) to ensure the tractor does not unexpectedly engage auto-steer, especially when driving on public roads. This code triggers when the two controllers read different states for the Auto Guidance / Master Roading switch (e.g., one controller reads the switch as "ON" while the safety controller reads it as "OFF"). It can also trigger if the steering valve controller is configured for the wrong steering valve type. When this crosscheck fails, the system defaults to a safe state and disables auto-guidance.

• MAXXUM T4E
• VESTRUM CVX
• AFS Connect Magnum Tractors (180, 200, 220, 240, 250, 280, 310, 340, 380)
• Steiger Tractors (335, 385, 435, 485, 535, 620)
• Vestrum CVX Series
• Maxxum
• Puma

1. 1

   Toggle the Master Roading / Auto Guidance switch manually back and forth a few times to clear a potentially stuck state.

2. 2

   Check the ISOBUS diagnostic page on the Pro 700 / Pro 1200 display to verify what state the system recognizes the switch is in.

3. 3

   Inspect the wiring harness and connectors between the Roading Switch and the Steering Valve Controller (SVC) for pinched wires, corrosion, or loose pins.

4. 4

   Test the switch with a multimeter to ensure both dual circuits open and close simultaneously (a failed pole will cause the crosscheck to fail).

5. 5

   Verify controller configuration if the steering valve or controller was recently replaced, as an incorrect dataset will flag this code on boot-up.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the battery to prevent electrical shorts during repair.

2. 2

   Access the Switch

   Remove the trim panel on the headliner or armrest console to access the back of the Auto Guidance / Roading switch.

3. 3

   Inspect and Clean

   Disconnect the switch harness. Inspect the connector for pushed-back pins or green corrosion. Clean with contact cleaner if necessary.

4. 4

   Replace the Switch (If Faulty)

   If the multimeter test during diagnostics showed a discrepancy between the switch's internal circuits, replace the switch with a new OEM unit. Snap the new switch into the bezel and reconnect the harness.

5. 5

   Check the Controller Connections

   Locate the Steering Valve Controller (SVC). Disconnect its main harness and check for moisture or corrosion, which is a common cause of crosscheck voltage mismatches. Clean and reconnect.

6. 6

   Software Update / Calibration

   If the switch and wiring are perfectly intact, the issue may be a software glitch within the SVC/SRC. A Case IH dealer will need to connect the Electronic Service Tool (EST) to re-flash the Steering Valve Controller software (e.g., to version 2.02 or later) and push the correct Advanced Steering Configuration dataset.

7. 7

   Clear Codes and Test

   Reconnect the battery, power on the tractor, and clear the fault codes. Perform a steering spool movement test and verify that the auto-guidance engages properly in the field and locks out properly when the roading switch is activated.