My sons 07 civic coupe just quit running the other night. I had him towed and then figured it was the alternator. I replaced it and he drove the car home which was about an hour away. The car ran fine. Today he drove about 45 mins in the am and he said the battery light came on and then went out. Car ran fine. He was driving home from work today and says the light would come on sometimes when he gas it but would cut off when sitting still. I am lost on where to start. Help please.