Battery, alternator and your battery wires going to the main fuse box under the hood. Mine looked fine but were corroded. A resistance test (Ohmeter) shoul do the trick. They should have very very low resisitance if you read more than like... maybe half an ohm then replace them. The ground is cheap maybe 7 bucks but your positive wire is best from the dealer because it will fit perfectly. Up to 50 bucks, talk about getting boned, but the wire replacement is usually a good idea.