Case IH 15259 - AST – AST (R1 module): Steering valve main or safety controller demanded safe state

The cut-off solenoid is stuck open, which causes the spool movement test to fail during the transition from on-road to off-road operation.

• MAXXUM T4E
• VESTRUM CVX
• Farmall 40
• Farmall 45
• Farmall 50

1. 1

   Access On-Board Diagnostics: Enter the diagnostic mode by navigating the 'H menus' using the switches on the instrument cluster.

2. 2

   Navigate to the AST System: Go to the R1 module, select menu H3, and select the AST system (press the dimming key to accept). The lower LCD should display 'ch - - '.

3. 3

   Verify the Spool Movement Test: Verify if the synchronization between the steering valve main and safety controllers is failing during the cut-off solenoid test when transitioning from on-road to off-road modes.

4. 4

   Inspect the Solenoid: Check the steering valve's cut-off solenoid electrically and mechanically to confirm if it is physically stuck open due to debris, binding, or an electrical short.

1. 1

   Locate cut-off solenoid

   Locate the main steering valve block and identify the cut-off solenoid.

2. 2

   Inspect electrical harness

   Disconnect the electrical harness to the cut-off solenoid and inspect the pins for corrosion or damage.

3. 3

   Remove cut-off solenoid

   Remove the cut-off solenoid from the steering valve block.

4. 4

   Inspect valve spool and plunger

   Inspect the valve spool and the solenoid plunger for scoring, debris, or mechanical binding that would cause it to stick in the 'open' position.

5. 5

   Clean or replace solenoid

   Clean the spool and valve body thoroughly. If the solenoid is internally shorted or the mechanical binding cannot be resolved by cleaning, replace the cut-off solenoid.

6. 6

   Reinstall solenoid

   Reinstall the solenoid and reconnect the wiring harness.

7. 7

   Clear fault codes

   Use the instrument cluster (R1 module, H3 menu) to clear the stored fault codes.

8. 8

   Test repair

   Test the repair by transitioning the tractor from on-road to off-road mode to ensure the spool movement test passes and the safe state is no longer demanded.