Power Steering Pressure Switch: Description
WARNING: This page is about a different car, the 2002 Jeep Wrangler. However, it is still accessible from the selected car via links, so may be relevant.
A pressure sensing switch is included in the power steering system (mounted on the high-pressure line). This switch will be used only on vehicles equipped with a 2.5L engine and power steering.
Courtesy of DAIMLERCHRYSLER CORP.