Coming from your vehicle there should be a black wire with a pink stripe which is your ignition switch wire. you know how when you turn off your ignition it turns off the radio? (prevents dead batteries) Well this wire triggers it. if it doesnt get power, your radio will never turn on thinking the ignition is off.
This black wire with the pink stripe should be attached to the Red wire coming from your radio

2000 SVT Black/Tan #1633/2150 (a few mods) Alpine: CDA-9835, MRV-F540, MRD-M550 PG: TANTRUM-X 6.5 COMP all around. Some people wear Superman pajamas. Superman wears Chuck Norris pajamas. CEL currently: Off