air/fuel gauge with switch

[holokosta]

Hey Guys,

My car has an air/fuel gauge with a switch next to it, it came with it when I purchased the car...

I realize the switch could be for anything, but can some one explain without telling me to turn it on and see what it does (because i've done this numerous times and doesn't seem to do anything...) what it could possibly be for? Tuner perhaps, maybe it was power to the gauge???

I'm just looking for some input because i'm trying to trace down what may or may not have been modded on the car before I bought it..

Thanks!