How Does an Ignition System Work?

The ignition system used in cars today has evolved significantly over the years. The early days of car ignition systems utilized the camshaft as the primary timing method.

This mechanical system combined with basic electronics produced the spark for many cars and still does. As the technology improved, ignition systems evolved to depend on the on-board computer to control the delivery of the spark. This was a significant improvement in both accuracy and dependability.

In this article, we will look at the evolution of the ignition system and what you can do to ensure that it stays in tip-top shape.

how car ignition system work

What is the Ignition System?

The ignition system in a car is responsible for producing the spark at each spark plug at the right time.

There are basically 3 types of ignition systems in use today. They are; Distributor based (mechanical), Distributor-less (electronic) and Coil-on-plug (electronic). Each system improved on the one before it, so let’s look at the evolution of the ignition systems over time:

  1. Distributor

This early type of ignition system is connected to the camshaft with gears. In this type of system, the camshaft turns the main distributor shaft inside of the distributor. The distributor cap has 4, 6, or 8 evenly distributed electrodes that connect to each spark plug with a wire. Inside the distributor, a set of points rub against a multi-sided cam. The cam opens and closes the points at a specific time to produce the spark.

This type of system was inherently prone to wear and tear which reduced efficiency. To improve efficiency the design evolved to using solid-state switches. This improved reliability but did not remove the dependency on the distributor shaft. As the camshaft, gears and distributor shaft got older, more slop between components developed and efficiency of the system was reduced. This system also utilizes a single coil to produce the spark for each of the spark plugs.

  • Distributor-less

To solve the efficiency problem the system needed to evolve. In the early 1980s engineers developed a distributor-less electronic ignition system.

This type of ignition system produces a spark based on two shaft position sensors and the on-board computer. The two sensors are the crankshaft position sensor and the camshaft position sensor. Information provided by the positions of these sensors is continuously fed into the computer. This system significantly improved the efficiency and reliability of the ignition system. This system improved the production of the spark by dedicating a coil for every 2 cylinders and generating a stronger spark.

  • Coil-on plug

Another significant improvement to the ignition system came a few years later. This type of ignition system utilizes all the components found in the distributor-less system.

The biggest difference is that instead of 2 cylinders sharing a single-coil, each cylinder has its own dedicated coil. The advantage of this design is that the coil wire is eliminated so the spark is much stronger and much more reliable.

How to start a car with a bad ignition switch

The basic concept of delivering a spark to a spark plug probably won’t change anytime soon. This is a given, but improvements are always in the works so never say never. As mentioned in the descriptions of the different ignition systems, there are several important components that are common to all the systems. Here is a list of car ignition components:

  • Coil – produces the spark
  • Distributor cap – connects each electrode to the appropriate spark plug
  • Rotor – distributes the spark to each electrode inside the distributor cap
  • Points – controls when the spark is delivered to each electrode inside the distributor cap
  • Distributor shaft – opens and closes the points
  • Car ignition switch – master switch that controls power to the cars electrical ignition system and accessories. It also routes power from the battery to the car’s starter to crank the engine.

How to Start a Car with a Bad Ignition Switch

There are ways to bypass a bad ignition switch to start your car. The process is not simple and usually requires a bit of expertise under the hood.

Car technology is so complicated that the best way to avoid being stranded by a bad ignition switch is to be proactive.

Here are a few symptoms that may point to a problem with the ignition switch:

  1. Car stalls while you are driving. May indicate that the ignition switch is intermittently cutting off power to the ignition and fuel system, causing the engine to stall. If this is happening, you should bring the car in for an inspection of the ignition switch.
  2. The car starts and then suddenly stalls. This is a good sign that the ignition switch is at fault. Time to bring it in to get the switch replaced.
  3. Car accessories do not power on. If you cannot power on accessories when the ignition switch is in the “on” position, it probably means the switch is bad. Although the switch may still start the car, it is time to take it in and get the switch replaced.

The ignition switch is the most heavily used switch in the car so over time it is going to wear out. Unless you have special expertise in bypassing the ignition switch, it is best to heed the warnings and be proactive.


All cars (except diesel) need a spark produced by the ignition system to complete the combustion cycle in each cylinder.

The ignition system’s job is to ensure that the spark plug fires to ignite the air/fuel mixture during the compression stroke. Over the years several methods have been devised to accomplish this.

As described above, these methods ranged from mechanical distributors to sophisticated electronic systems that utilize the on-board computer. The goal with each new type of system was to deliver a hotter spark and improve reliability and efficiency.


As with any system that involves multiple components, proper and periodic maintenance is important. In this article, we have explored the ignition system and some of the key components. As we have seen normal wear and tear is a very big factor. This is especially true in the distributor-based system.

We have also seen that the ignition switch plays a very big role in the operation of the ignition system. The other major component that will cause engine misfires, rough idle or loss of power is a faulty coil. The coil is one of the ignition systems most important components because it produces the spark. With that said, there are things that you can do to keep the ignition system operating smoothly, these include:

  • Check the coil output voltage
  • Inspect and correct distributor points gap
  • Inspect and replace a rotor that looks worn
  • Check the distributor cap for interior moisture which may indicate a crack or leak
  • Address any symptoms of a potential ignition switch failure
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