Best thing to do is confirm with a voltmeter. The sleeve should be negative, tip positive. If reversed, I would suggest reversing the wires on either the receptacle or the adapter.
The adapter is "probably" protected against reverse polarity but not sure. At best, it simply would not work if receptacle is "backwards".
How long have you been using it? Any issues?Woody's Custom Shop offers a positive to negative ground changer. I installed it in the supply line for the cigarette lighter, so i can use all the modern equipment with a stabilized 12V voltage up to 4 amps.
http://www.ebay.com/itm/NEW-6-8-12-...Parts_Accessories&vxp=mtr&hash=item35d6937f76
You can also buy a cigarette lighter extension cord and rewire it. That is the cheapest solution.
http://www.amazon.com/s/ref=nb_sb_noss_1?url=search-alias=aps&field-keywords=cigarette lighter extension&sprefix=cigarette lighter e,aps&rh=i:aps,k:cigarette lighter extension&tag=theampfor-20
I use the ground converter because of my lack of attention. Someday i would plug my electronics in without the changing adapter and it my die.
A really easy solution is just to wire in a lighter socket in a plastic box so it is insulated from the chassis, then wire it correctly. You'll get as much power as usual and it's cheap and easy. You could even wire one in at the end of a cord and wrap it in electrical tape. Or cut the cord after the lighter plug and reverse the wires. So many ways.....
I did change my car to negative ground though since I was doing a full restoration. And installed an alternator.
Pertronix ignition modules are built for either positive or negative ground. They cannot be switched around so you will have to buy the correct one if you convert the cars polarity.
John Friese
67 White
67 Red