New Holland 15500 – Steering Controller: Primary Steering System Pressure Low – Secondary Steering System Operated

The primary steering system's hydraulic pressure has dropped below a critical threshold, triggering the activation of the secondary steering system. The secondary steering system is a backup safety feature designed to provide temporary steering control in the event of a primary system failure. This condition limits the performance of the steering system and requires immediate investigation to identify the cause of the low pressure.

• T8 Series
• T9 Series

1. 1

   Check for other active fault codes (e.g., 15501, 15502, 15510, 15512, 15520, 14020) which can provide diagnostic clues regarding sensors or CAN communication.

2. 2

   Check the hydraulic fluid level and ensure it is within the recommended operating range to prevent air introduction.

3. 3

   Inspect the hydraulic fluid for signs of contamination, such as a milky appearance (water) or metallic particles.

4. 4

   Visually inspect the steering hydraulic system for leaks, damaged hoses, or loose connectors at the primary steering pump, steering orbital motor, steering cylinders, and lines.

5. 5

   Examine the wiring and connectors for the primary steering pressure sensor and secondary steering system components for signs of corrosion, damage, or loose connections.

1. 1

   Address immediate safety concerns

   Because the secondary steering system is active, the machine's operational capacity is limited. Move the machine to a safe location and shut it down.

2. 2

   Test hydraulic pressure

   Connect a pressure gauge to the primary steering hydraulic circuit to measure the actual pressure. Compare the measured pressure to the specifications in the service manual.

3. 3

   Test primary steering pump

   If the pressure is low, the primary steering pump is a likely culprit. Test the pump's flow and pressure output directly. Replace the pump if it cannot maintain the required pressure.

4. 4

   Inspect pressure relief valve

   If the measured pressure is low, check the pressure relief valve in the primary steering circuit. A faulty or incorrectly set valve could be dumping pressure.

5. 5

   Test primary steering pressure sensor

   If the hydraulic pressure is found to be within the correct range, the primary steering pressure sensor may be faulty and sending an incorrect low-pressure signal. Test the sensor's output and compare it to actual system pressure. Replace if faulty.

6. 6

   Check for internal leaks

   Inspect for significant internal leaks within the steering orbital motor or steering cylinders that could lead to a loss of pressure.

7. 7

   Verify secondary system function

   Once the primary steering system issue is resolved, verify the proper deactivation and function of the secondary steering system.