A rule of thumb?

[Andy]

I bought led turn signals with one each red and white wire. Can't find the instructions so don't know which is ground.
Is red hot and white ground as I'm trying out my feeble memory here?

[John Schmidt]

Andy, no rule of thumb because different manufacturers use different colors. It shouldn't hurt them by simply testing them on a 12v source. Just try it with red as ground and white on 12v, if they don't light up simply reverse the wires and try again. I have an external connector for my Battery-Tenda hook up, I just stick the wires in there to test lights. Never had an LED fail after testing like mentioned above.

[Kingbee]

White "should" be ground, but no harm done if hooked up wrong.

[Grandpot]

My thumb said, "Vote for the white wire being ground."

Like John said, hook it up one way, if it doesn't work hook it up the other way.  You will not damage it.  ???

[Madmike]

If you hook them up backwards do they absorb light??????????

[Grandpot]

Madmike:

Yes they do and then the stored light can be used later.

Did you ever try to calculate the speed of dark?

[Andy]

Thanks y'all

[R J]

You can usually figure the following colors are ground.

White,
Green,
Brown, or
Black.

Reds are usually hot wires in 99.9% of the cases....