Oil pressure gauge help

[Kevin]

So I wanted to put an aftermarket oil pressure Gauge in. Simple enough right? I used the sender that came with the gauge. It's an autometer carbon series. There is 3 tabs at the back of the gauge.
One says Gnd
one says S
and one says I
so I figure gnd is ground, I is power and S is the signal from the sender. So that's how I hooked it up. It didn't work. It actually went backwards??? Lol
so troubleshooting I hook it straight to my battery thinking maye there was somethig wrong with my power or ground. Nope nothing. I tried switching the I and S wires and then it goes to max with the car off and back down to zero wth car on
I tried hooking it up to my friend's car (he has defi gauges though) an same thing.
Is it just my wiring? Or my gauge is garbage?

 

[kneedragger85]

 

[Kevin]

Ignition switch is where I put the 12v?

 

[kneedragger85]

Well, yes but it's a 12v source that's only on when your accessories or ignition is on. A popular 12v source is your cigarette lighter.

 

[RazoE]

make sure it's switched 12v, otherwise it's going to always be on..

 

[Kevin]

right so i am hooking it up right. at first i hooked it up in the car but it didnt work.. so i tried directly to the battery using alligator clips but it reads either all the way max or all the way negative.. as i mentioned in the first post.
so is my gauga broken??

 

[RazoE]

does your original work..?

 

[Kevin]

yes.