I need help identifying which wire is which inside my USB cable. So I stripped the outer insulator for the USB cable, and it revealed 4 wires: Red, White, Green, and Yellow.
I thought Red would be VCC, but then I checked the circuit board for the mouse I ripped it off of and the board labeled where the four wires were soldered on.
It showed four characters each associated with a wire color: V (White), G (Green), D (Yellow), C (Red). Very strange from what I have learned about USB so far, but strangest being that Red is not VCC! Why is there no standard for these wire colors?
Anyways, how can I confirm which is which (VCC, GND, D-, D+)? I have a multimeter, and confirmed that between White and Green, White and Red, and White and Yellow, there is 5V. I don't think that is much of a development, but what should I do?
I do have other USB cables lying around as well, but that's an easy way out and my absolute last resort. Thanks.
Answer
It's easy to just test the connectivity from the pins on the connector-end of the cable to the bare wires at the other end.
Even a hardware store multimeter is good enough for this test.
Disconnect the cable at both ends. Set your meter to the ohms function.
Touch one probe of the meter to one pin of the connector. Touch the other probe to one of the wires. If the wire is connected to the pin, you'll see (near) zero ohms. Depending on your meter you might also get a beep for continuity.
The pin assignments for the connector are readily available. Here's a picture from Wikipedia: 
If your connector is a mini or micro type, those pinouts are also available from the Wikipedia article on USB.
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