Segr Stratus

Good morning
I have Stratus is model 2000 etaba psibles loose cables and I found several one of Nadamas that I found a disconnected sensor is the one that goes at the exhaust outlet has 4 cables I do not know very well what they are but what happens that it does not have harnes only the 4 cables the color is 1gris, 2blancos, 1 black I would like to know how to identify the voltage of the earth and the other two cables of the sensor