Radio Testing

In a nutshell I Use a spare 12 volt car battery with a jumper wire from the radio's red wire going to the positive terminal on the battery. Another wire from the neg bat terminal to the side or rear mounting stud for the support bracket (provides a must-have ground), hook up a speaker to the speaker terminals and finally an antenna. Hook the orange wire to the pos bat terminal to check the light.

EDIT: this is for a factory radio which uses red for power, orange for the light and green and some other color for the speaker leads. Aftermarket radios are of course different