How the Ignition System Works – Diagram & Breakdown

Many people may be confused as to why their 12V battery isn’t sufficient to start cars directly. Well, the truth is that you will need more than 12V to power your engine (Probably between 30-40V, depending on your engine).

This is where the ignition system comes into play. Your vehicle’s ignition system is responsible for starting its engine. It consists of several parts that work harmoniously to ensure combustion happens when you start your engine.

I will explain in simple layman’s terms the workings of an ignition system diagram (step-by-step). Also, we will cover the ignition components and operation and how to troubleshoot issues with the system.

Ignition System Diagram

How does the ignition system work?

You are probably wondering how your car’s ignition system components works, especially if you keep having difficulty starting your vehicle. You aren’t alone here; depending on your car, the ignition can be very complicated. The ignition coil wiring diagram above helps to simplify the process.

However, regardless of how complicated the system is, they all follow some basic principle and must have some vital components to work well.  This principle is what I hope to explain subsequently.

One of the earlier components listed was the battery. Now, regardless of what model or kind of ignition is used in your car, the battery must be present. It is from the battery that the “primary current” is derived.

Connected to the battery is the ignition switch. Just like your basic switch at home, the ignition switch allows you to turn on or off the flow of electrical current into other ignition parts.

Once current is allowed to flow after the switch is turned on via a key system or button, current should flow into the ignition coil. I want you to envision the ignition oil like a transformer for our discussion. So, how would you describe the function of a transformer?

You would typically say that it is used to step up or down the current that flows within an electrical circuit. Unlike this definition, the ignition coil steps 12.0V to the high voltage needed for ignition. It does this by a process called winding. The effect of the winding is to induce a magnetic field around an iron pole running in the middle of the coil.

As the winding continues, the magnetic field also grows to the extent that it will collapse and need to escape. Where it goes is into your distributor and then into your spark plugs.

The distributor does more than just distributing the excess collapse magnetic field. It also helps to switch off the magnetic field.  Furthermore, the distributor is a camshaft that rotates and distributes electric charge. As it opens, it induces a spark that is amplified by the spark plug. Most modern ignition systems are designed with a timer within the distributor to control when the spark happens.

What are the basic parts of the ignition system?

The following are major parts of the ignition system diagram you should be familiar with:

The Ignition or starter switch:

The ignition switch is an important part of the system and begins the entire process. Just like the normal function of a switch, it controls the flow of current from the battery to other parts of the system. It is also responsible for supplying the voltage the ECU and starter control module needs.

The Ignition Distributor

The distributor’s primary responsibility is to transfer high voltage to each spark plug of your car. It can be seen at the tail end of the ignition system, and it will also be responsible for powering the coil.

However, it is worth noting that newer ignition systems are designed without a distributor. These distributorless ignition systems have no timing adjuster moving parts and, therefore, reduce engine drags.

12V Battery

Your car’s battery is the source of the primary voltage absorbed into the ignition system. As we have said earlier, primary voltage is insufficient to start your vehicle, hence the ignition system’s reason.

The Ignition coil:

The coil usually acts like a mini-transformer for the ignition system to help convert that low voltage into something higher to meet the standard voltage required.

Spark plugs

This part of the ignition system is connected to the distributor and creates the necessary spark for combustion.

How do you troubleshoot an ignition system?

Below are the recommended tests to help you troubleshoot what may be wrong with your ignition system:

1. Check the condition of the spark plug:

I recommend that all my readers begin their troubleshooting with the spark plug. For this test, you will need a spark plug tester.

Disconnect the spark plug distributor cap and connect the tester. Then, crank the car; the tester should light up if voltage is transferred.

If there is no spark, then it’s most likely that the fault is coming from the ignition coil. You can change the plugs if you suspect them to have gone bad.

2.  Inspect the Distributor:

Begin by removing the distributor cap and cranking the engine.  Check for spark at each opening point as it is cranked. It could be that the cap is responsible for the car distributor problems.

If there is no spark, then check the power coming from the coil. You can do this by blocking the point coming from the coil with cardboard or testing it with a multimeter.

3. Inspect the condition of the coil:

For this test, we will be making use of a multimeter tester. Set your multimeter on resistance as measurements. If the coil is good, you should have continuity from one point to another. However, if there is no continuity, it is most likely that the coil is open or burnt.

First, remove your coil wire and connector so you can access the terminals easily. Ensure your multimeter is set on resistance. Connect each terminal to the multimeter. The meter should read up if it is working fine.

4. Inspect the Ignition module:

The last check for fault is the ignition modules. A lot of issues can develop with your vehicle’s ignition modules. Faults may include burnt connection, wiring or fuse, damaged module, or software problems.

Our test will start with physically inspecting the ignition module, fuse, and connection. You want to check for burnt smell, colorization, cut wiring, or blown fuses. Use an OBD scan tool to detect fault with the modules easily.


We began our discussion by explaining how your car’s ignition system works. While some vehicles have different ignition system models, they follow similar principles, examined here. Also, a quick look at the various parts of the system was deemed necessary.  We concluded by explaining how to troubleshoot faults with some of these parts.

Thank you for reading, and I hope you found our article helpful!!


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