alright got the new o2 sims today (splice in kind), and i just want to double check on the install... its a 4 wire sensor... 2 grounds (white), which i dont want to touch 1 signal wire (black?), which i cut, and place the one wire sim into..(just a resistor) 1 heater wire (color?), dont touch this wire ethier so what is the signal wire? and what is the 4th wire color/what does it do?