The control valve is stuck or inoperative.

1. Clean the control valve. Refer to Power Steering Pump Replacement
2. Replace the control valve, as needed. Refer to Power Steering Pump Replacement

The pump ring is worn.

Replace the pump ring, as needed. Refer to Power Steering Pump Replacement

The pressure plate is scored.

Replace the pressure plate, as needed. Refer to Power Steering Pump Replacement

The thrust plate is scored.

Replace the thrust plate, as needed. Refer to Power Steering Pump Replacement

The rotor is scored.

Replace the rotor, as needed. Refer to Power Steering Pump Replacement

The pressure plate is broken.

1. Clean the pressure plate. Refer to Power Steering Pump Replacement
2. Replace the pressure plate, as needed. Refer to Power Steering Pump Replacement

The thrust plate is broken.

Replace the thrust plate, as needed. Refer to Power Steering Pump Replacement or Power Steering Pump Replacement .

The vanes are sticking in the rotor slots.

1. Clean the vanes. Refer to Power Steering Pump Replacement
2. Replace the vanes, as needed. Refer to Power Steering Pump Replacement