When it get dark , it will turn on the width light and headlight automatically ( only control the low beam) . This sensor control by two stages . When it start getting dark , the width light will turn on firstly , when it become darker , then the headlight turn on . When day break , both headlight and width light turn off automatically . When the car getting through a tunnel , the light will turn on . exit the tunnel , light off ! Leaving home and coming home function. Fit for below vehicles: For Aveo 2012 For Chevrolet Cruze 2010 2011 2012 2013 For Opel Astra j 2012 2013 2014 2015 2016 2017 2018 2019 The module is directly connected between the original car switch and the wiring harness. Install method: White connect to ACC +12V(Only when the key is in ACC or ON state can output) Red connect to power +12V (This is the battery 12V, no matter what the state of the key, there is output) Warm tip: Use fuse box cap or multimeter to find these position. Colour: black Material: ABS Package Contents: 1 x Headlight Switch Control Module Sensor Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.