Is this a new car to your family or has it just started happening? I would imagine it could be either wired incorrectly or a short somewhere.
Either way, I'd recommend getting an auto sparky to look at it!
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Currently in scatz's garage: The purple burble that is the Subaru Legacy GT-B, 280BHP of twin turbo goodness!!!! Also now have a 2002 Scenic 1.6 16v Authentique!!!!