Cam Position Sensor
Moto Guzzi Quota 1000 and Quota 1100 ES models
Thanks to Charlie Taliaferro for providing this information on the Yahoo! Guzzi_Quota news group. In Charlie's own words:
The Cam Position Sensor is Magneti Marelli SEN813. I can find NO cross reference, but it is used, apparently, on some late-model Aprilias. The sensor showed resistance of about 600+ ohms between a couple of the leads when the magnet is excited with iron (I used a pair of pliers), then drops back down when the iron is removed. The other lead measured about 0.4 ohm, and also moved when the magnet was exposed to iron.