As technology advances, more electrical components are being added to vehicles, from safety features to entertainment upgrades. More devices means plenty of wires and complicated arrangements to keep everything in line and working properly. It is not as simple as running the wires from each part to one power source, and there are a variety of methods for distributing power and ensuring that it gets there without issue.
Many parts of the car, including the alternator, starter, radio, power seats, sunroof, and windshield wipers relies on electricity to work properly. The wires and switches that connect these devices are called circuits. When the car is running, electricity is sent from the engine to the circuits to power the many different tools that drivers rely on.
In order for these components to work, the correct amount of electricity is needed, and some devices need more juice than others. Power seats and windows will take more to run than an interior light, for example. In most cases, switches are used to open and close the circuits, but the instruments that need more power, such as the fuel pump or the fog lights, rely on relays that can handle more electricity.
Circuit breakers are employed to protect the circuits from drawing too much electricity. This can happen when you are attempting to adjust a power seat, but there is something behind it that is preventing it from moving. If you continue to attempt moving the seat, the circuit breaker can step in and cut off the electricity flow when it gets too high.
Circuit breakers work much like those in a residence, but they do not require a manual reset. In most cases, they will automatically return to normal once they have cooled down. Because of this, they are typically installed near the instruments they protect or on the engine's fuse block.
There are a number of components that need a constant flow of power to function, and in this scenario, many vehicles use fusible links to protect the circuits from damage. The most notable application of a fusible link is in the circuit that provides power to the alternator and battery. This part is susceptible to melting, which can render the vehicle immobile. It may also be difficult to diagnose this issue, as the wire often melts inside of the insulation and no damage can be seen by the naked eye. Many newer models use a maxi fuses in place of fusible links. These blade fuses provide low heat dissipation and time delay, which can prevent overheating that would otherwise melt a fusible link.