I'm not even close to an electronics expert but to find 12+ and GND why don't you just take a DC voltmeter and start probing??? I mean it's just positive to negative right? if you get it reversed the multimeter should tell you because it's polarized. not sure what a K line is but if it has a specified voltage like 5 volts, than you should be able to find that if you know which is ground right? what am I missing here?