Autometer AIT gauge Q's

[MVDyken]

I recently bought a AIT gauge. there is this mystery blue wire on the back of the gauge and do not know what itis for. the instuctions don't say anything about the blue wire. Please help.
Note I have the Black temp. box too

[Clark's diesel]

I recently bought a set of Autometer guages. I had a few questions myself and went to Autometer's website. My questions were all answered the very next day. I'd give that a try.