hey i gut an 87 gt that im doing a mass air conversion to, i have the harness 19lb mass air meter and a compter out of an 88 lx. the mass air harness is a 4 wire harness w/ red black orange/blue and green/red wires. i assume that black red are power and ground and the other 2 are signeal wires but which one is positive and which one is negative? can anyone help. thanks