Case IH NH15008 – Steering Controller: Change Valve Solenoid Open Circuit

The electronic control system has detected a break in the electrical circuit of the change valve solenoid, which is part of the Fast Steer, Adaptive Steer Control, or Autoguidance system. An open circuit prevents the electrical signal from the control module from reaching the solenoid, disabling its ability to activate and switch steering ratios for low-speed maneuverability.

• Puma 165
• Puma 180
• Puma 195
• Puma 210
• Puma 225 CVX
• Maxxum Series
• MXU Series

1. 1

   Visually inspect the wiring harness leading to the change valve solenoid for cuts, abrasions, or corrosion, and ensure the connector is securely fastened.

2. 2

   Perform a continuity test on the wiring between the Steering Controller and the change valve solenoid to check for breaks.

3. 3

   Measure the resistance across the disconnected solenoid terminals (an infinite reading indicates an internal open circuit in the coil).

4. 4

   Test for voltage at the solenoid connector with the key on and the fast steer system activated to verify power supply from the control module.

1. 1

   Ensure Safety

   Before beginning any repair, ensure the tractor is on a level surface, the engine is off, the parking brake is engaged, and the key is removed.

2. 2

   Access the Solenoid

   Locate the change valve solenoid, which is typically on the steering motor or a dedicated hydraulic valve block for the fast steer system. On New Holland T7 tractors, the steering pump is located on the right side of the engine.

3. 3

   Repair or Replace Wiring

   If diagnostic checks reveal a break in the wiring, repair the damaged section using appropriate connectors and sealing methods to prevent future corrosion. If the harness is severely damaged, it may need to be replaced.

4. 4

   Replace the Solenoid

   If the solenoid itself is found to be faulty (open coil), unscrew it from the valve body (be prepared for a small amount of hydraulic fluid to leak out). Install the new solenoid, ensuring any O-rings or seals are correctly seated, and torque to the manufacturer's specifications.

5. 5

   Reconnect and Test

   Reconnect the wiring harness to the new solenoid.

6. 6

   Clear Fault Codes

   After the repair is complete, use a diagnostic tool to clear the NH15008 fault code from the Steering Controller's memory.

7. 7

   Verify Operation

   Start the tractor and test the operation of the fast steer system to ensure the repair was successful.