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HelloCustomer you definately have an issue. The alternator sounds like it's charging. If the battery is at 9.9v when you start either there is an electrical drain on that battery or the battery is bad, draining itself. The stability service light may be due to low voltage and when this problem is corrected, that might go away. To find the drain will not be a problem for a qualified repair facility. Since it is a Cadillac, there are so many circuits and several fuse boxes throughout the car, that finding the short yourself, could be a little involved. Concentrate on what is draining the battery, then see if you have any warning messages show up.
Your JA Expert,