No, the headlights are not tied in to the rain sensor. The fact that the lights came on when the wipers were on was coincidental. The auto headlight was just responding to the changing light levels during the rain.

On a side note, my 330xi the headlight washers are tied in to the lights. The headlight washers only come on if the headlights are on. I don't have headlight washers on my X5 so I don't know if it's the same.

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