Bentley manual has wiring diagrams (not much help if you don't have one though).

Did you check the fuse panel in the right rear of the hatch as well as the fusible links in the left side of the spare tire well (towards the passenger compartment)?

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual