How does your car’s electrical system work?
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Knowing more about how your car’s electrical components work can save you unnecessary trips to the mechanic or—worse—expensive tows.
All fuel-powered engines have the same basic components that make up a vehicle’s electrical system. It doesn’t matter if you’re riding a 1967 Shelby Mustang Fastback or a heavy-duty work vehicle, you’ll find all of these parts under your hood:
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The car battery is responsible for every electrical component in your car, from the blinkers to the dashboard to the radio. The battery helps start the car, but it’s also responsible for providing the car with an even energy supply. You probably know from experience (or just from how batteries work) that if the battery dies, your car won’t start. A battery can last up to five years, but harsh Canadian winters and bad driving habits (like forgetting to turn the lights off) can reduce its lifespan.
Here are common signs that your battery might be on the fritz:
- It takes a few seconds longer to start.
- Your Check Engine light comes on.
- Your car battery starts to smell like rotten eggs.
- Your battery case looks bigger than it used to.
- Your battery is over three years old.
Is your car having battery issues? Read this car battery guide for helpful advice.
The alternator gets its name from its primary function, which is to generate alternating current (you know, the AC in AC/DC). It converts mechanical energy into electricity, which powers everything in the car and recharges the battery. Here are common warning signs that your alternator is failing:
- The warning light comes on (don’t ignore this).
- You have trouble starting the car.
- The headlights appear weak or start to flicker.
- Rattling or clunking noises.
The starter motor works alongside your battery to start the car. In the few seconds needed to insert the key into the ignition and turn it, an entire series of fantastic mechanical feats take place in careful and quick succession. During this rapid process, the starter motor is employed to turn the engine over to allow it to suck in enough air and fuel to cause combustion.
If you hear a loud click or a grinding sound when you try to start the car, your starter motor may be loose or needs to be replaced.
Wires, connectors and fuses
All the electrical components of your car are connected by a series of cables. They’re located throughout the car all the way to the trunk and are covered with insulation. Wires vary in diameter and are colour coded according to their voltage. Connectors make cars easy to service because they allow a mechanic to reach in and remove the faulty wires.
Fuses are in charge of keeping wires at a stable temperature. Your car likely has two fuse panels: one in the glove compartment and the other in the engine compartment. You can use a continuity tester to find out if the fuse is blown or simply pull it out and take a look.