Was removing the fans in order to swap serpentine belts prior to getting my AC system pumped down (in order to change the compressor), and this thing managed to get knocked off. I have no idea what it's for, and figured you guys could help out.

 

was the connector that goes to it yellow? if so, it's part of the airbag system.

 

Yes, it was. I got it back in place and secure, so all is good.