Auto Headlight Mod for 2007 300 Touring

[SpudNuts]

I just bought my wife a 2007 300 Touring and have a question about auto headlights.

The model that we bought didn't come with auto headlights but I did find here a mod for other models. I decided to pull off the headlight switch knob and take a look.

I was able to manually switch to the "A" setting and it works. After removing a small plastic tab on the knob it now turns to the left past the off position freely. The problem is that I don't think we have the climate sensor installed because the lights come on with ignition and off with ignition and stay on night and day.

On the dash there is a round device or spot that would be a climate control sensor but don't think there is anything there.

Questions:

1. Is the wiring there for the sensor?
2. Does anyone know where I can buy the sensor?
3. Are there instructions anywhere that I could use to replace or add the sensor?

Thanks much for any replies.