ok the black wire is the ground for sure. the white ones should have one black line through one, which is the negative for that channel. The gray should too. splice into your rear speaker wires being sure not to cut through them, which is a pain in the ass to fix. You will have to use both signals from your rear right and rear left speaker channels. read the manual of the loc to see if the white is the right channel or left. if you need any help PM me cause ive had alot of crap dealing with locs for my friends.