Toyota Charging system Malfunction (Solved & Explained)

There are a few reasons why Toyota drivers will see Charging System Malfunction or Check Charging System message on their vehicle’s dashboard. They left their vehicle in key on mode which drains the battery, there’s an issue with the electrical wiring in the charging system, or there’s an issue with the alternator.

What is a Toyota Charging System Malfunction?

What is a Toyota Charging System Malfunction?

The Toyota company has developed many new systems for their vehicles so they can run more efficiently. One of those systems is the Toyota charging system. The Toyota charging system is now installed in many Toyota vehicles.

This system works directly with the electrical supply inside the vehicle, including the voltage regulators and the alternator. It is an essential part of the Toyota vehicle, as it is directly linked to the battery inside the engine. 

So when the Toyota Charging System Malfunction light turns on, it is best to heed the warning and take the vehicle to the Toyota Service Center as soon as possible. 

But what is a charging system malfunction? It is a warning that alerts the driver to any issues with the charging system. There are 4 main reasons ‌ the Charging System Malfunction Light turns on out of nowhere.

Key on, engine off – Some Toyota owners accidentally leave their vehicle on key on engine off mode and this drains the battery.

The electrical charging system has a wiring issue – there are many cables and wires that make up the electric charging system. When one of these wires is not working correctly, he could throw off the performance of the battery as well as the alternator.

The alternator is bad – The alternator is a device inside of the engine that Harvest mechanical energy and turns it into electrical energy. It is through the alternator that the combustion engine can power the battery.

A sensor is not working correctly – There are several sensors placed around the battery, as well as the alternator. When the sensors are not working correctly, the charging system malfunction light will turn on Siri without the sensors, and the computer inside the engine will not know if all the components are performing correctly.

Charging system malfunction is common in the following Toyota models: Camry, Corolla, Yaris, Rav4, Fortuner, and Highlander.

How to fix the system malfunctions

Wiring issues – If there is a wiring issue, then consider disconnecting the battery. This will trigger an onboard computer reset. You will have to find the battery

Wiring issues

The battery is completely drained – When the battery is completely drained, you will need to turn on the engine to charge the battery. If the battery cannot hold a charge, then it could be the alternator messing up the charge.

A bad alternator – since the alternator is one of the key components of the charging system, when it goes bad the entire system will fail. Depending on the Damage Done to the alternator, the mechanic may be able to repair it.

But if the alternator is completely damaged, then you will need to replace it completely. Replacing an alternator is a cheap repair job. The average cost range for replacing an alternator is $500 to $1,000. That is the price of both parts and labor.

If the alternator is not repaired or replaced in time, there could be serious repercussions. The battery could be permanently damaged, and you will have to replace the battery. Replacing a battery costs thousands. 

A bad sensor – If a sensor has gone bad, then you will need to find that sensor and replace it. There are multiple sensors around the engine and around the charging system and battery. You’ll need to test each sensor to see which one is no longer working. 

You may be able to do this at home, but a certified mechanic will have the tools and instruments they need to test every sensor quickly and find the one that is no longer working. Once the sensor is found, then the mechanic can replace it with a new sensor. 

There could be multiple damaged sensors. Mechanics must inspect the damaged sensors and discover why the sensor went bad. Some sensors go bad because they come into contact with coolant or fluid. 

If there is loose liquid damaging the sensors, then that means there is fluid leaking and damaging other parts of the engine. 

bad sensor

What can a Toyota driver do to prevent issues in the future?

Looking over the battery and testing the charging system on a regular basis can prevent future issues from suddenly impacting the performance of the vehicle. It will also keep your charging system working correctly.

In order to properly test a charging system, you or a trained Toyota mechanic must look over the alternator, voltage regulator, and the battery. Look for any surface issues like nicks and dings, damage from fluids or acids, or any other sign of wear and tear. 

Even if you don’t have much experience with vehicles, testing your Toyota charging system is quite easy. Here’s what you need to do:

  • First, turn off the engine. Then, set the parking brake on and put the gear in neutral. Place a wedge underneath the wheel to prevent it from Rolling. Allow the engine to cool down. It’ll be easier to work with a cool engine than a hot one. 
  • Be sure to check the voltage gauge on the dashboard. It should read at 12 volts when the car is turned off and at least 14 when it is turned on. If the voltages are not at 12 and 14, then there is an issue with the alternator.
  • Now, open the hood of the car and check for any signs of damage anywhere around the engine. You can also check any fuses that you can see. If there is a blown fuse, that could directly affect the charging system.
  • Check the battery cables for any sign of damage or corrosion. Replace any cables that are Beyond repair or frayed.
  • Check the alternator connectors and tighten them if they are loose.
  • Check the engine for any signs of fluid or coolant leaking.
  • Once you have checked all the components, turn off and turn on the car and reset the system.


Leaving the engine on key mode engine off, a damaged alternator, bad sensor, and wiring issues can cause a charging system malfunction. You can inspect the battery charging system along with the alternator, the cables, and fuses by yourself in your own home.

  • Eric Williams

    I'm the founder of Daily Car Tips. I wrote articles in the automotive industry for more than 10 years, published in USA and Europe. I love sharing my knowledge and insights with fellow enthusiasts. Join me on this journey as we explore the exciting world of cars together!

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