The fluid level is low.

1. Inspect the fluid level. Refer to Checking and Adding Power Steering Fluid .
2. Add fluid as needed. Refer to Checking and Adding Power Steering Fluid .

The pressure plates and vanes are scored.

Replace the components as needed. Refer to Power Steering Pump Replacement or Power Steering Pump Replacement .

The pump shaft bushing or bearing is scored.

Replace the pump shaft bushing or bearing as needed. Refer to Power Steering Pump Replacement or Power Steering Pump Replacement .