The Ford F250 electrical systems are powered by its alternator, which also charges the battery when the engine is running. The alternator keeps electricity supplied to the truck stereo, the instrument panel, windshield wipers and the brakes and steering. If the battery malfunctions, the alternator can keep the vehicle running. If the alternator stops working, the battery will be drained; the electrical systems will shut off, and the vehicle will not be able to restart with the malfunctioning alternator and drained battery. The alternator must be changed. This task can be completed at home.
Disconnect the battery, by taking the terminal connectors off the positive and negative terminals. Move the terminal connectors into a position away from the battery, so they cannot touch the terminals while you are changing the alternator.
Loosen the lug nuts on the front passenger side wheel, so they can be easily unscrewed once the vehicle is off the ground.
Place tire blocks under the rear wheels, so the truck will not move while you are working. Jack the front end of the vehicle and, using either jack stands or cinder blocks, rest the weight of the truck. You will be working primarily on the passenger side of the truck, but the entire front end needs to be elevated.
Remove the lug nuts the rest of the way from the wheel, and take the tire off the vehicle.
Unhook the serpentine belt by applying pressure to the tension wheel. Check the serpentine belt for disrepair, while it is off of the vehicle. It will save time, money and aggravation to change it during this process, if it needs to be changed. The serpentine belt is connected to both the engine and the alternator and facilitates a transfer of power from the engine to the alternator. It is then transferred to the electrical systems, as well as back to the engine.
Unscrew the bolts on the alternator bracket, until the alternator moves and the belts are able to be slipped off. Unscrew the wires from the alternator, and remove it from the truck.
Plug the wires into the new alternator, and slip it onto the bracket. Reinstall the belt, and bolt the alternator down. Do not tighten the bolts completely. Adjust the tension on the belt, by pulling the alternator down, while tightening the bolts.
Reinstall the tire. When the truck has been let down, connect the battery terminals.
