On the 3 prong cigarette lighter. Which connection is pos, neg, and ground?

I have to splice the 2 prong lighther wires to the 3 prong connection. I tried the left and right connectors but got nothing. There are two other possibilites left seeing as the bottom connector must be pos. or negative.

Thanks!

 

I think mine is a orange wire. I would buy a test light they are really cheap. Then you never have to ask anybody anymore.

 

Got it...Trial and Error works well in some cases.

So, facing where the wires come out....

Left (+)
Bottom (-)
Right (not used)