When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I would guess that it has to do with the AIR pump.
Down in the left headlight bucket area is an electric air pump that feeds air to the exhaust manifolds. It is controled as to when to come on and such... there is a valve array that directs the air to the manifolds.
IIRC, it comes on at start up, to help light off the cats.
I will have to check my FSM to get more details...