The fluid level in the pump is low.

1. Add power steering fluid, if needed.
2. Inspect the pump for leaks. Refer to Power Steering Gear and Pump Leaks .

The pump belt slips.

Replace the belt. Refer to Drive Belt Replacement 5.0/5.7L or Drive Belt Replacement 4.3L or Drive Belt Replacement 6.5L Diesel or Drive Belt Replacement 7.4L in Engine Mechanical.

The flow control valve sticks.

Replace or clean the control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle .

The pump pressure is insufficient.

Refer to Power Steering System Test .

The gear relief valve is faulty.

Replace the gear relief valve. Refer to Steering Gear Check Valve Replacement - Off Vehicle .