so ive been installing my friends system for a couple days know and he got an alpine iva-d300. the question is on the parking brake/lights wires. i tired many combinations of hooking them up to gdn and power wires. some of the time it works but when we try the same procedure anothertime, it doesnt work. please help me out guys its driving me crazy. theirs two wires that have to be hooked up.