It's located on the rear view mirror.
Mine quit working just recently,I had my X for almost 2 years now.
Wires are ok.

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e53 '00 4.4i Oxford Green II Freshly rebuilt tranny(2nd one) and transfer case/front shaft
e70 '08 3.0si Sapphire Black cinnamon leather 7 seats
e61 '06 530XI Sports Touring Silver - SOLD