It may not be necessary to wait for sleep mode. Try measuring the draw with the key off and then removing one fuse at a time to see if amp draw reduces. 42 is vanity mirrors, 43 and 45 are instrument cluster and 44 is airbag control module. If removing a fuse one at a time does not locate the draw it may be that it is not going into sleep mode at all. It should go into sleep mode in about 16 minutes. If it does the amber light for gearshift position will go out. It may also be worthwhile to check for error codes.

What year X5 do you have? Would be best to add year and engine to your signature, almost always needed to help.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas