This is worth a shot as ive heard from other enthusiasts it can fix electrical gremlins that are random, ive tried it myself once and it worked. Mine was driving down the road and stereo started cutting in and out, then my nav unit started turning on and off on its own and half opening/half closing would not stop even if i turned the car off...

Got to the battery in the trunk undid the positive and negative terminals then i touched them together for 10 sec (apparently resets the modules etc) hooked the batt up everything working fine.

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2006 X5 4.8is Fully Loaded