If you post the vehicle year make model, I might be able to get you the color codes for the wires, other wise if you have a multimeter, just connect the negative lead to a chassis ground and the positive to one of the wires, whatever one you find continuity at is the ground. This method works in most cases, unless your vehicle uses some sort of common ground system.
The color code system lynellia is linking to is a standard for after market only, every car manufacturer uses different color codes.
Update: Are you talking about the wires coming from the radio? In the factory harness or do you have an after market radio, and you want to know what are grounds in the harness?
If it is factory harness, use the same method I explained, if after market, it will be in the manual, or the color code lynellia linked to.
1400 days ago