Any idea what this is?

[smithma7 at gmail.com (Mike Smith)]

While pooking around under the hood today, I noticed this item.  It
was unplugged. Still is as it doesn't want to cooperate and I don't
want to force, but finesse.

Anyway, in the first image (wide shot) it's in the green box.  Found
it under the radiator overflow tank. In the second image (close up),
the plug in the green box plugs into the spot in the red box.

http://www.grum.com/temp/red5/

I've never seen it before.  Any ideas?

-- 
Mike
'86 red 16v: Red 5 (aka der Jahrtausendfeierfalke)
"The world is my oyster soup kitchen floor wax museum." - King Crimson