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Did you have the actual alternator output tested?
If the battery warning light which is the symbol of the little battery is illuminated along with the brake warning light 99.9% of the time this means that the field circuit in the alternator has failed. That light only becomes grounded when the alternator stops charging on the field circuit side.
11.67 volts is not enough this should be at least 13.5 idling. The Alternator is not working.