3 position toggle switch on dash
 

I just bought my second PSD 2002 CC -250 Lariet. Has had 5" banks exhaust and turbo mods along with AFE fileter cool air box and I do not know what else. There is a small 3 position toggle switch on the Dash. Is anyone aware of any flip chip systems using this method. I am assumming that it is something to do with the chip. Not sure though. Anyone else know or seen this before???? Thanks in advance.

The switch is very small silver 3 position toggle down, center, up

My guess is that it's an exhaust brake utilizing the stock EBPV or a torque converter lock switch. What happens when you swtich it? Changes to the way the truck runs, shifts, exhaust sounds, etc...

Diablo makes a 3 position "Sport" flip chip and they use a small toggle like you described.
Check to see if there is a gray cable leaving the toggle going to the PCM.