“Trac Off” and Check Engine Light in Toyota: Car Shaking. Why?

When the car starts shaking, and both Check Engine and Trac Off Lights illuminate your Toyota's dashboard, it can feel like the fastest way to a mental breakdown. But fret not. This article will cover why you may be experiencing those symptoms and how to diagnose and fix the issue.

Let's start with what the lights could mean.

Traction Control Off light highlights

• Common reasons:issues in traction control function
• How to fix:disconnect the battery for some time, read the codes
• Possible consequences:vehicle's behavior may change
• Priority level:High
• Can you drive?Carefully
• DIY repair:Impossible
• Repair price range:$200-$850

What Do the "Trac Off" and the Check Engine Light Mean?

The Trac Off Light comes on in the dashboard if the traction control system is disabled. The traction control system is a feature in modern vehicles that helps maintain control and stability. It works along the vehicle stability control system. The features kick in when driving on low friction or slippery road surfaces. This can be muddy, unpaved, or roads filled with ice. Using the feature on normal roads is not advisable since it reduces fuel economy. 

The traction control system uses wheel speed sensors to gauge each wheel's rotation speed. If a wheel slips, it automatically applies brakes to maintain traction in slippery conditions. It also shifts power from the skidding wheel to other wheels with better traction.

When you manually switch off the traction control system by pressing a button at the side of the steering wheel, the Trac Off Message illuminates the dashboard. The message can also come on whenever the traction control system malfunctions. Instead of the Trac Off message, other car models can display an icon of a car with wavy lines running in the opposite direction of the car tires. 

On the other hand, the check engine light is an orange, amber, or yellow warning light that comes on in the dashboard whenever there's an engine-related issue. Depending on the situation's urgency, it may come on flashing or continuously illuminate the instrument cluster panel. If the check engine light is flashing, it indicates a severe engine problem that requires urgent attention.

It's not advisable to ignore the warning light and continue driving. Doing that can cause further complications, which may damage the engine. The Trac off and the Check Engine Lights can come on simultaneously.

This could be due to an engine-related issue causing the Trac Off light to illuminate. That happens because the vehicle switches off the traction control system in a self-preservation mechanism to prevent it from getting harmed by the engine-related issue.  

What are the Causes of the Car Shaking When the Check Engine and Trac off Lights are on in Toyota?

When the car shakes and both lights illuminate the dashboard, the most common issue is a cylinder misfire. When an engine cylinder misfires, it fails to produce power through the combustion reaction.

A cylinder misfire can happen in one or more cylinders in the engine. One telltale symptom of a cylinder misfire is excessive jerking or vibration that can cause your car to shake. Below are the potential reasons the cylinders may misfire, leading to the illumination of the Trac Off and Check Engine lights. 

1) Ignition System Issues

Ignition system issues such as faulty spark plugs and defective coil packs can cause your cylinders to misfire, leading to the car shaking. Let's look at how each can cause the shaking.

• Faulty Spark Plugs

The spark plug is a device that produces an electrical spark that starts the combustion process of the air-fuel mixture in an engine cylinder. The ignition gets the engine running by putting the cylinder pistons into motion.

If the spark plug becomes faulty, the fuel inside the cylinders won't burn effectively. This can lead to excessive engine vibrations while the car moves at low speeds or during idling. The engine vibrations make the whole car shake. You'll also likely hear a loud noise from your engine area and experience fluctuating RPMs.

• Defective Coil Packs

An ignition coil pack is a collection of ignition coils. The role of the ignition coils is to boost the voltage from the car's battery high enough to produce a spark at the spark plug. This fires the cylinder by igniting the air-fuel mixture and allowing your vehicle to start.

A voltage overload can cause the coil packs to overheat. The heat may then damage them, causing them to fail. Other causes of defective coil packs are exposure to moisture and high temperatures. When an ignition coil fails, the engine misfires. Sputtering, hesitation, jerking, or vibrations during everyday driving follow. 

2) Fuel-Related Issues

• Faulty Fuel Injectors

Fuel injectors act as spray nozzles in an internal combustion engine and deliver fuel to an internal combustion engine through atomization. Atomization is the conversion of liquid fuel into tiny liquid droplets or mist.

This is in preparation for emulsification (mixing it with air) and vaporization (changing it to a rarefied suitable for use in an internal combustion engine). The corresponding cylinder misfires when a fuel injector turns faulty or becomes clogged. This is because it can't deliver adequate fuel into the cylinder, causing the engine to vibrate while striving to complete each cycle with insufficient energy.

The result is engine vibration and a loud knocking sound. With the engine vibrating, the car will also shake, and the Check Engine and Trac Off lights appear on the instrument cluster. 

• Bad Fuel Pressure Regulators

A pressure regulator's function is to maintain a correct and consistent pressure for fuel injectors in different driving conditions. When fuel pressure regulators malfunction, they can cause low pressure, making the engine run lean.

This results in slow engine performance. On the flip side, if the pressure becomes too high, the engine runs rich. This increases engine emissions and causes misfires. A reduced fuel economy can also result from both low and high pressures. 

3) Exhaust System Issues

• A Clogged Catalytic Converter

A catalytic converter eliminates harmful gases and pollutants from the exhaust by filtering, burning, and converting them into harmless forms. The converter can also improve fuel efficiency and economy.

When the catalytic converter experiences issues such as clogging, it can lead to the gas inside the engine heating up until it ignites, causing the engine to misfire. The misfire causes engine vibrations, and when the problem takes time to fix, it can cause engine damage. 

• Exhaust Leak

The exhaust system directs gases out of the vehicle through the exhaust pipe. The exhaust system also muffles the sound from the engine, preventing noise pollution. Exhaust leaks from exhaust system components can direct the harmful gases inside the car, which can be toxic for the passengers to breathe.

A leak can also cause loud sounds such as ticking, raspy, or tapping, often confused with an engine knock. The sounds become more audible during acceleration. Exhaust leaks can also cause the lights to illuminate on the dashboard and cause engine vibrations. Another effect of a leaky exhaust system is the decline in fuel economy.

How to Diagnose Your Toyota Car Shaking with the Trac Off and Check Engine Light on

Making the correct diagnosis will help you to find the proper fix. That's why diagnosis is the most important aspect of finding a solution to your issue. Below are the steps to make a diagnosis:

1) Use the scanner

The first step to make a diagnosis is to use a diagnostic tool called an OBD II scanner. It provides codes that help to determine the source of the problem. The device is widely available online, in auto or repair shops.

To use it, ensure the ignition is off. Using the diagnostic link connector, connect your diagnostic scanner tool. Turn on the ignition without starting your engine to power up your scanner tool. Allow the device to complete the boot sequence and enter the requested information on the scanner.

You can then read the Diagnostic Trouble Code (DTC code) present. The device may also present multiple codes with brief descriptions. Conducting an online search by keying in the codes in the search bar will help you get more detailed and reliable information about your issue.

2) Check the ignition system

You'll need tools like a spark plug tester and multimeter to troubleshoot your ignition system. Start by visually checking the spark plugs for any signs of fouling or damage. If you don't find any damage or fouling, you can use a multimeter to test the plugs and verify the recommended manufacturer's values.

\If the values are correct, inspect the spark plug wires for decay and damage and check their resistance. The next component to check would be the ignition coil pack. A spark plug tester comes in handy when testing the coil pack.

An alternative is using a multimeter to test the primary and secondary internal windings. If you find the spark plug or ignition coil faulty, your best option is to replace it with a new one.

3) Make sure the fuel supply system is OK

To diagnose the fuel system, ensure the fuel pumps efficiently pump the fuel to the injector nozzles. Check whether the injector nozzles have any signs of clogging or damage. You can also test the fuel delivery by checking for correct fuel pressure and volume under different operating conditions.

The testing comprises two areas, which are performance-related diagnostics and no-start diagnostics. If you find an issue with the injector nozzle or pressure regulator, replace it with quality new ones from recognized brands. 

4) Exhaust system troubleshooting

To diagnose the exhaust system, check for leaks from components such as mufflers, catalytic converters, and internal and external exhaust manifolds. Signs of excessive corrosion on exhaust system parts can also signify future cracks or leaks. The next step is to inspect the catalytic converter.

If you notice extreme heat under the converter, it's likely to be clogged. Other symptoms are black smoke from the exhaust with a characteristic smell of rotten eggs. To fix an exhaust system issue, weld areas with exhaust leaks to ensure they are leak-tight. A clogged catalytic converter will need replacing. 

Bottom Line

There you go-possible reasons why your Toyota is shaking, and Check Engine and Trac off lights come on in the dashboard. If you find that diagnosing and fixing is not in your wheelhouse, take your car to the dealership or find a qualified mechanic to do it for you.