teleflex 12 volt gage wireing

[48tony]

I have a pergo battery switch hooked up.How do i wire in a 12 volt gage so i can get 2 seperate volt readings when switching from batt 1 to batt 2 or vise versa?One terminal has the letter I on it as i am sure that wire goes to my starter silinoid so the gage only gets power with the key on.1 ground terminal ground to motor.1 power terminel for gage light ethier splice into the I terminal or go to running light switch this way the light only is on when needed at night vs on all the time.there is a other terminal with the letter s on it not to sure of this one.Butt if i hook the gage up the way i have spoke of above will this be correct and when switching the pergo switch will it give me 2 seperate volt readings .I do not want to fry something out do to my lack of ele no how. thanks tony