One goes to the starter, the other goes to the alternator on the other side of the engine and runs in a harness along the back of the engine. Both are in wrapped and taped harnesses that run underneath the battery tray and mounts. If you plan on replacing them completely set aside 4-5 hours that you can have the car down as you'll need to remove the battery, tray, and air box and undo the harnesses under all that. Then you have to put it all back together again. While you are doing it you might as well replace the line that goes from the starter to the main fuse box with an 8-ga line.