The electrical energy that the Toyota alternator generates is necessary to supply the never-ending needs of the engine and the many accessories that are now standard on your vehicle. A properly operating Toyota alternator will be capable of producing 13 volts or more. If it is producing more than 13 volts, the excessive amount will be dissipated by the voltage regulator and no damage will occur to your electrical system. If less than 13 volts is being generated by your alternator on your Toyota, then the engine and accessories will be drawing power from the battery which in time will become depleted of energy. There are many symptoms of a failing alternator that a driver of a Toyota will be able to notice. When it is not producing enough electrical current, one of the most obvious signs is the dimming of the head light when traveling at night. The driver should be able to notice that as their speed increases, the illumination from the headlights will diminish when the alternator is failing. The testing and inspection of the electrical generating system can be done by simply starting the engine then turning on the headlight. The reason for activating the headlights is because they will instantly draw the most current from your electrical system. If the headlights are dim or become dimmer as additional electrical components are switched on, then the alternator is faulty and should be replaced on your Toyota. The charging of your battery to operate your vehicle will only last so long before you become stranded on the road with a dead vehicle and a tow truck will have to be called to provide assistance to you and your passengers.