I got a USB wire from an old mouse and the wires were soldered to the circuit as: Green - D, Orange - C, Blue - V and White - G.
Assuming orange was red and white was black; they should be VCC and GND respectively. Meaning they transmit power.
However I found that the green and blue writes could power a LED, with blue being positive and green negative. The other two couldn't.
I don't have a voltmeter to check so I was wondering whether the wires were mixed up or if this is normal. If the wires are mixed up, how do I separate D+ from D-?