Can A Bad Car Battery Cause Computer Problems?

Have you had a recent car battery problem, and you’re wondering if it can affect the performance of your car’s computer? You’ve come to the right place, for we have researched this question, and we have the answer for you.

All electronic components of your car—including the car computer—can be affected by a bad battery. A faulty battery can cause computer problems if it cannot supply it with the electrical energy that it needs.

Several problems can come from a bad car battery. Find out all about it—including the problems you can get from a bad PCM—in the succeeding sections. Read on!

pulling up an car old battery for replacement, Can A Bad Car Battery Cause Computer Problems?

What happens when you start your car?

Let’s take a closer look at how your car starts because this is where your battery plays an important role. Once your car has started, the alternator takes over from the car battery to provide the electrical energy that the electrical components of your car need.

starts a car engine in car

Starting the ignition

An internal combustion engine is an example of a feedback system. Feedback systems rely on inertia to move from one cycle to another indefinitely. However, it needs the input of an external force to initiate the cycle.

When you turn your car key to start the engine, the car battery sends a large amount of electrical energy to the starter motor to initiate the engine's combustion cyclee. Once the engine has received enough inertia to move on its own, the starter motor is disengaged.

If the battery cannot deliver the required electrical energy to the starter motor and other electrical components during ignition, then the startup will fail, and the car will not start.

The PCM controls the ignition timing. If it cannot get the power that it needs during ignition, the engine will not get the right mix of fuel and air at the right time.

The engine cannot start without the right fuel-to-air ratio. If it cannot get the right fuel-to-air ratio, then the car will not start.

What happens when the engine will not start?

If the engine cannot start, the alternator will not receive any mechanical energy. The alternator converts mechanical energy from the movement of the engine into electrical energy.

Once the alternator receives enough mechanical energy, it converts it into electrical energy. It will then take over the battery in providing electrical energy.

However, without the mechanical energy from the engine, the alternator cannot take over the battery, and the battery will be left with the task of providing electrical energy to all the electrical components that your car needs to start.

What are the signs of a bad battery?

Car battery light in dashboard warning

The bad thing about a car battery is that it can die slowly. A dying battery will cause several problems for your car while it is dying.

The good thing is that these problems are signs that tell you it is time to replace the battery.

Hard or slow to start the car

This is a common and classic sign that it is time to replace the battery. You turn your car key to start the engine, and you hear your engine cranking and then nothing. There is a sluggish whirring sound like your car needs another cup of coffee, and it takes time to start.

If you experience this more and more during cold starts, then it is time to replace your car battery.

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The engine cranks but wouldn’t start

A long cranking sound from under the hood means that your starter motor is trying to start your engine, but it is not getting enough power to do so. Cranking but failing to start is a good sign that you need to replace the battery.

If all you get when you turn the key is a clicking sound, then it could also be a problem with the starter motor.

Dash light works, but the car will not start

When you get this scenario, this could mean that the battery has enough power for the dash lights but not enough for the starter motor.

Keep in mind that the dash lights are LED lights, and they require only a small amount of electrical energy. The starter motor, on the other hand, requires that the battery is close to full charge to function properly.

This is also a scenario where the problem could be with the starter. However, it is best to eliminate the possibility of a bad battery first before going for the starter.

Need jump starts more often

If you notice that your car needs jump starts more and more often, then this means that it is time to visit your local car battery dealer. Car batteries are like cell phone batteries. Their ability to hold a charge gets worse as they age. A car battery, on average, lasts for two to three years.

What does the battery light mean?

It is a common misconception that the battery light will turn on to warn you that it is time to replace the battery. Most people think that their battery is still working fine because they do not see the battery light on the instrumentation cluster while they’re driving.

Seeing the battery light doesn’t mean that it is time to replace the battery. The battery light will turn on when your car is running on battery power. This means that if you see the battery light turn on while you’re driving, then that means that your alternator is not providing the electrical energy that your car needs.

In this case, it is time to check the alternator for problems.

What are the symptoms of a faulty car computer?

An engine control unit (ECU) in the engine bay

Now that we’ve discussed the problems that you’d experience from a bad car battery, let’s talk about the problems you’d go through if your car had a bad computer.

The modern car computer or the PCM (Powertrain Control Module) is in charge of important car components like the engine, the transmission, and the powertrain. It manages these systems based on the information that it receives from the many sensors inside your car.

The succeeding sections give you the most common symptoms of a bad PCM.

These symptoms do not always lead to a bad PCM. There are situations where the true culprit is a bad sensor or a short in a circuit. Thus, it is best to have your car checked by an expert mechanic when you start to experience these symptoms to determine the true cause of the problem.

The Check Engine light is on

The Check Engine light is like a jack-of-all-trades when it comes to warnings. It tells you that there is a problem with your car that is not covered by the other warning lights.

This is both a good thing and a bad thing. It is a good thing because it isn’t always a bad problem when you see the Check Engine light. However, it still means that there is something wrong.

Many states will not allow a car to pass an inspection if the Check Engine light is on. This means that you’d have to take care of the problem represented by the Check Engine light sooner or later.

The car will not start, or the car starts roughly

Just like what we discussed at the beginning of this article, the PCM can cause your car not to start. If it doesn’t get the right amount of electrical energy, then it will not function properly.

If you’re sure that your battery is not the culprit, then this is another sign that there could be a problem with the PCM. Unfortunately, it is best to have the PCM checked and fixed by a professional mechanic since you need special equipment to check the PCM.

Bad mileage

One of the functions of the PCM is to coordinate with the ECM (Engine Control Module) and the TCM (Transmission Control Module) to determine the optimum fuel-to-air ratio. It also determines when the best time is to shift gears while you’re driving your car.

A malfunction with the PCM will cause bad mileage due to a bad fuel-to-air ratio and less than optimum shifting.

Ensure that your tires have the correct air pressure and that you are following your maintenance schedules for the replacement of oil and filters. If both of these are okay, then it could be a problem with your PCM.

Failed emissions test

Check up car battery life

Since the PCM determines the correct fuel-to-air ratio, a wrong mix can cause more than the normal emissions. This will cause your car to fail the emissions test.

Engine stuttering or stalling

This symptom is caused by a mechanical problem in the engine or a malfunction in the PCM. A bad engine timing is usually the root cause of this problem.

However, the PCM is the easier and cheaper route of repair. Thus, it is best to have your PCM checked if you experience this issue.

Erratic shifting

Erratic shifting can happen because of a faulty sensor. This can also be caused by a faulty PCM or TCM.

A problem with the PCM can cause your car to get stuck in gear which could lead to an expensive transmission repair.


pulling up an car old battery for replacement

A dying battery can cause the PCM to malfunction because it cannot provide the electrical energy that it needs.

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