Cadillac Repair Questions? Ask a Mechanic for Answers ASAP
The next thing you need to do is have the car diagnosed for the power saving mode message displayed on your dash.
There will be a code set in the vehicle for this, possibly in the BCM or PCM.
Your alternator is not being turned on, could be a wire or terminal problem at the alternator connector, or within the harness.
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I hope my advice has been of assistance to you.