Cigarette lighter wiring question?

[benwellington]

So I hooked up an FM modulator on my vibe, and tapped power and ground from the cig lighter. But I blew a few fuses along the way.My question is on a cig lighter, is the center inside 12V or the outside "shell" (the part you can see sticking out)? According to the markings on the lighter in my vibe, the screw and middle inside are ground and the outside "shell" is 12V. THis seems wrong though. However, my modulator had markings that said 12V and ground on the wire. The only way I was able to make it work was by hooking up the wire marked ground to the shell (marked 12V) and the "12V" wire to the center (marked ground on the vibe). You could see how this was confusing. I blew 3 fuses before I tried reversing. (go radio shack!)Thanks!Ben

[esjones]

I don't know about the Vibe specifically, but I thought that, in general automotive electrical systems, the "shell" of the lighter, as you put it, would be ground (negative), while the center contact (the 'tip' on the 12V plug) would be +12V.I've used my laptop computer 12V adapter and a couple of cellular phone 12V cords in the Vibe, and this is how they all work.

[benwellington]

I thought so too. Thanks for confirming.It is very strange. When you open up the lighter in the vibe, the markings are reversed on it, or at least in mine they were? It says right on a metal tab coming off the "shell" 12V. And it says 0V on a tab touching the middle. grrr.. ben

[ragingfish]

Your best bet is to use a multimeter...that should be able to tell you which is +12 and which is ground.

[Jahntassa]

Cigarette lighter plugs are always center positive. Some of them are switched power, some of them are constant power, but they are ALWAYS center positive.

[mcgusto82]

i concour. center is positive.