A little on the pricey side, IMHO, but looks like it might be the right harness

But one could sell the module to recoup some of the purchase price.





BMW X3 E83 X5 OEM trailer wiring harness with module | eBay

Mike

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Mike
Dallas, TX & Appleton, WI
2003 E53 4.4i Pearl Beige
2003 E46 330Xi Monaco Blue
2007 E90 335Xi Black Sapphire Metallic
2011 F25 X3 28i Black Sapphire Metallic