Hi i have a 99 interstate and the alt.went bad --over charge --blew headlight fuze --replaced it and had one side --now i replaced alt. blew battery --replaced it --when i put in new headlight blub it only works on high --wont go down to low --do you think it could be a bad switch --or headlight relay --i dont really know where to start --i hate to pay some shop big bucks to find this --is there anything to look at before i take it to a shop --could a headlight relay cause this ? ill be thankful for any help !!!!