my 2005 BMW X5 will lose power (when driving or just running) it will read errors on 4x4 inactive, transfailsafe, all lights will come on and will lose power. The battery ultimately dies for a little while, if i remove key amd let computer reset it will work fine usually. It does this whenever its cold outside. Ive had it into multiple shops and they have got nothing. Maybe a short somewhere? Any ideas where to look next? Thank you for any help!
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Hello, my initial reaction is that the vehicle really needs a strong battery for good reference voltage at all times. If the battery is weaker than it should be, multiple electrical concerns could occur, as well as a lack of adequate power driving or running the engine. Have your battery professionally tested to see if it passes and is able to handle a good load and is fully charged.
Your charging system could also be at fault, not powering the battery well enough to maintain that reference voltage.
Start with these areas. If everything tests "good" then you'll have to look into the individual systems - 4x4, transmission, engine, and so forth and seek concerns that could share a single source, like a ground issue on a common circuit, or something of that nature.
