Your 2004 Ford Focus needs a working alternator in order to function properly. The alternator supplies electrical power for the various accessories on the Focus, including the control modules, fuel system, air bags, environment controls and various other electronically powered systems. Once the alternator dies, the Focus can operate on battery power for an hour or two, but after that, your Focus won’t move again until your replace both the alternator and battery. Anyone with basic automotive-repair skills, some good physical endurance and a basic set of tools can replace a Focus alternator in a few hours.
Things you need
Battery wrenchLug wrenchJackJack standBelt-tensioner toolSocket setTorque wrench
1 Open the bonnet and support it with the prop rod. Disconnect the negative cable end from the battery using the battery wrench.
2 Loosen the lug nuts on the right-front wheel using the lug wrench. Jack the right-front off the ground and support it on a jack stand, placed under the frame. Remove the lug nuts and wheel by hand.
3 Plug the belt-tensioner tool into the belt tensioner and move the tensioner out of the belt path. While holding the tensioner aside, reach in with your other hand and take the belt off the alternator pulley. Carefully release the pressure on the tensioner.
4 Reach in through the open right-front wheel well and disconnect the alternator wiring using the socket set.
5 Remove the alternator mounting bolts with the socket set and pull the alternator out of the engine well, through the wheel well. You may need to turn the alternator to a different orientation in order to get it out, depending on the engine, alternator size and amount of clearance you have.
6 Compare the old alternator and the replacement one to make sure they’re both identical physically. Check to make sure the wiring connections and voltage regulator are in the same place. Compare the pulleys to make sure they are the same size, width and have the same number of belt grooves.
7 Move the replacement alternator into position, in the reverse manner of how you removed the old one.
8 Thread the alternator mounting bolts in by hand and then tighten the bolts down with the socket set.
9 Reattach the alternator wiring in reverse of removal. Reinstall the wheel and lug nuts by hand.
10 Lower the Focus off the jack stand, using the jack. Tighten the lug nuts down to 85ft-lbs. of torque using the torque wrench. Reinstall the negative battery cable.
11 Move the belt tensioner aside once more with the belt-tensioner tool. Slip the belt over the alternator pulley with your free hand and then allow the tensioner to move back into position. Remove the belt-tensioner tool and close the bonnet.