Friend's 2004 Focus ... dash lights would go dim, car quit, and check engine light indicated a fuel pump relay issue. Owner was advised to buy new battery. Car quit again; battery replaced under warranty. Car quit, battery replaced under warranty. (unbelievable, eh?). Took to Ford and received a $1,200 estimate for replacing fuel pump and relay. I found high resistance where multiple wires are attached to battery. We cleaned/soldered wires on both negative and positive terminals and problem has not returned.