Join Date: Aug 2006
Location: Arlington, VA
Thanked 14 Times in 12 Posts
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Assuming that the bulb is an incandescent type (regular bulb with a filiment), there's no positive or negative. You can hook it up either way.
If you want to be sure, use a multimeter to be sure that neither of the two black wires is connected to the light housing or mount. Most likely they're not, so you can hook it up either way and it will be fine.