Service charge system.light. is on. Informed the altanator is running fast.??

don't know what you mean by the alternator running fast?well it could very well be a big issue if the alternator is not charging.if it's not,the you'll be running off the battery,until it drains it soon,then you'll be stranded somewhere and it won't start back up.get the charging system tested.most parts stores will test it for free!