Low power steering fluid.

1. Add power steering fluid.
2. Check the system for leaks.

The pump belt is slipping.

Refer to Drive Belt Replacement or Drive Belt Replacement in Engine Mechanical (5.0L, 5.7L, and 7.4L) or Drive Belt Replacement in Engine Mechanical (6.5L).

Sticky flow control valve.

Replace or clean the control valve. Refer to Variable Effort Steering System Check in Variable Effort Steering.

Insufficient pump pressure.

Refer to Power Steering System Test .

Faulty gear pressure relief valve.

Replace the faulty gear pressure relief valve.