It is a nice feature. I recently picked up a E38 740i and that feature didn't work. In fact, for some reason it also was not defaulting to allow the dial to control intermittent speed. I ended up unplugging the sensor and then the dial worked so at least I had manual control of the wipers. But then whenever I drive the X5 I really enjoy that feature. It is a really nice thing to have when it works.

No ideas how to fix it however...

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2003 4.6is - SOLD
2003 M5 Imola
2008 Mini Cooper S
2011 Mazda CX9