Passive infra-red sensors are used in many applications to detect the presence of people, eg security lights. I expect that when those devices become faulty it is not the PIR device that has failed but some other component (most likely in the power supply).

On the sidebar there is a list of PIR modules, the linked pages include pinouts and whether there is an Arduino driver for them.

• PIR motion sensor tutorial
• Another PIR motion sensor tutorial
• How Infrared motion detector components work

If any referenced page no longer exists, try looking for its URL on http://archive.org.