The power steering fluid level is low.

1. Inspect the power steering system for leaks. Refer to Power Steering Gear and Pump Leaks .
2. Fill the power steering system. Refer to Checking and Adding Power Steering Fluid .

The pressure plates and vanes are scored.

Replace the power steering pump. Refer to Power Steering Pump Replacement .

The power steering pump shaft bushing or bearing is scored.

Replace the power steering pump. Refer to Power Steering Pump Replacement .