just need to know i have the pioneer deh-7800mp headunit and the wiring harness that comes with it on the Red wire there is a black plastic case on the wire idk if its a fuse or a circuit or what but just need to know Do i need that inorder for the headunit to work because i accident cut that piece off the wire because the wire was gettin really short so i need to know how i go on about fixing this? If i need to fix anything