With the key in the ON position, check between pin 7 of the climate control system control unit and earth that there is a voltage of around 5 VoltWith the key in the ON position check that there is a voltage signal, between pin 10 and earth and between pin 19 and earth of the climate control system control unit, proportional to the thermal energy present at the windscreen analyzed by the sensor photodiodes (signal less than 5 Volt)Pin out1 +5V2 left signal3 right signal