You must have heard before that all relays are considered as fuses but all fuses are not considered as relays. This can be confusing to someone who knows little about circuits. To make the concept easy to understand, you only need to keep in mind that fuses are used to protect electrical devices from high current. So each time the device is fed with more current than it can handle, the fuse steps in. it breaks the circuit and saves the device from blowing. Throw in a relay into the equation and the concept changes a little bit especially if you’re taking about Porsche fuses and relays. Read on to learn more.
Devices like the solenoid cannot function without relays. That’s because they require considerable current to run. The Porsche keyless system is a good example of not just a device but a whole system that relies on relays. This is of course, the most common functional difference between a relay and a fuse. As far as design is concerned, a relay features a small coil of thick wire around a central iron core. It also has an actuating switch whose main function is to energize the coil. As soon as the core is turned on and energized, it moves heavy duty contacts together. This allows high current to easily pass through the device. That is how a small switch gets to control a high current device. Other prime examples of devices that use relays include engine cooling fans, power tops, power windows, power seats, power antenna, horns and the air conditioning compressor.
There isn’t a single electrical device in your car that is not wired through a fuse. That sounds absurd but it’s true. Like already mentioned, they are designed to fail anytime too much current is drawn through them. This goes a long way to prevent heating of wired which leads to melting of insulation, which is a setback that can easily cause fire.
Unlike relays, fuses are simple in design. it has a thin, soft wire on the inside with a cross sectional thickness that is specific. The dimension matters a lot because it dictates the amount of amps that the fuse can carry before it melts. Too much amps and the fuse promptly fails, saving the rest of the car circuit from damage. In short, the fuse sacrifices its life to save your car. It is small, yet it does a lot.
Fuses are also easy to find. Nearly all Porsche models have their fuses at the fuse panel. Some models use in-line fuses though, which can be found beneath the dashboard and inside the engine compartment.
Think of fusible links as an advanced or a different class of fuses. They do exactly the same job as the fuses mentioned above. What sets them apart though is the fact that they are rare. They are also used in few Porsche models. They are molded, single purpose links in wires which are designed to easily melt under extreme conditions. Your Porsche’s schematic should show you their location and use. Keep in mind though, that they are almost always found inside the wiring hardness in the engine compartment.