New Holland 15591 – Secondary Steering Controller, Tractor Multi-Function (TMF), or Autoguidance controller: Battery Voltage Too Low to Run Secondary Steering Pump

The electrical system's voltage has dropped below the required threshold to activate the electric power steering system pump, which may prevent the steering system from operating correctly. Control modules prevent the activation of high-draw components like the steering pump during low voltage events to protect them from damage. The underlying condition is typically a problem within the tractor's charging and electrical system rather than a failure of the power steering pump itself.

• T8 Series
• T9 Series

1. 1

   Verify battery and charging system health: test battery voltage with engine off (should be above 12.5V), test alternator output with engine running (13.5-14.5V), and inspect terminals and main grounds for corrosion or looseness

2. 2

   Inspect fuses and relays associated with the steering controller and secondary steering pump (e.g., TMF/autoguidance fuse in the cab)

3. 3

   Examine the wiring harness and power supply wires leading to the secondary steering pump and controller for damage, corrosion, or loose connections

4. 4

   Check for other low-voltage fault codes that may indicate a widespread electrical issue rather than an isolated component failure

1. 1

   Address Battery and Charging System Issues

   If the battery or alternator tests have failed, replace the faulty component. Clean or tighten any loose or corroded connections.

2. 2

   Replace Faulty Fuses or Relays

   If a fuse is blown, replace it with one of the same amperage. If a relay is suspected to be faulty, test or swap it with a known good relay of the same type to confirm the fault.

3. 3

   Repair Wiring

   If any damaged wiring is found, repair or replace the affected section of the harness. Ensure all connections are secure and protected from the elements.

4. 4

   Replace the Secondary Steering Pump/Motor

   Before replacing the pump, ensure the hydraulic fluid level and quality are correct, as hydraulic issues can sometimes be misinterpreted as electrical faults. If all electrical checks pass and the fault persists, replace the secondary steering pump motor.

5. 5

   Replace the Controller

   In the rare event that all other components are functioning correctly, replace the control module responsible for the secondary steering system.