I just bought a netami air/fuel ratio gauge come with 5 wires 2 for +,- of ilumination +,- for switch and other to the o2 sensor signal cable but im not able to find out where is it and wich one ofe the sensor is the one to use !!

 

Check out thai mazda 3 club in the internet. They have a comprehensive service manual that may provide what you are looking for.