Case IH 15249 - AST – Steering Valve Controller: Steering valve spool out of neutral at power-up

When the tractor's electrical system is powered on, the position sensor (LVDT) on the electro-hydraulic steering valve detects that the internal spool is not resting in its centered (neutral) position.

• MAXXUM T4E
• VESTRUM CVX
• Case IH Steiger
• Case IH Magnum
• Case IH Puma
• Case IH Farmall

1. 1

   Inspect the electrical connector at the steering valve (4-pin connector) for corrosion, backed-out pins, or damage to rule out a faulty LVDT sensor or wiring issue

2. 2

   Perform a ramp test and a step test using the dealer diagnostic tool to observe the spool's reaction and verify if the sensor reading changes

3. 3

   Check if the steering valve spool is physically stuck due to cold, thick hydraulic oil or internal debris

1. 1

   Preparation

   Ensure the tractor is off, the handbrake is applied, and hydraulic pressure is relieved.

2. 2

   Removal

   Label all hydraulic hoses connected to the steering valve to ensure correct reinstallation. Disconnect the solenoid/sensor electrical connectors. Remove the mounting bolts/nuts to take the valve off the tractor.

3. 3

   Inspection & Internal Repair

   Remove the end cap on the steering valve to access the spool. Inspect the spool centering mechanism (springs) which are responsible for returning the spool to neutral. Replace any broken springs. Check for internal plugs that may have backed out or fallen off the spool. If a plug has fallen out, clean the threads, apply a dab of Loctite, and reinstall the plug. Clean any debris from the bore and spool.

4. 4

   Reassembly

   Reinstall the spool and cap. If the valve bore is scored or the LVDT sensor is permanently failed, the entire steering valve assembly must be replaced.

5. 5

   Installation & Calibration

   Mount the valve back onto the tractor, reconnect all hoses and electrical connectors. Top off hydraulic fluid and run an autoguidance steering valve calibration procedure via the Pro 700 / armrest display to recalibrate the neutral position.