As a brand Toyota’s have an international reputation for durability and reliability. Many people will remember the 2010 BBC Top Gear program where a Toyota was placed on top of a building that was demolished. Even with all the damage that the vehicle suffered, the Toyota still started.
In most instance it is simple to diagnose and repair a problem in the unlikely event that your Toyota does not start. Three things must happen for a Toyota to start, the engine must turn over, petrol and air must be delivered in the right quantities to the engine and the spark plug must fire.
The easiest way to diagnose a Toyota Corolla engine that won’t start is to focus on these three factors. Start with the simplest solutions and work your way through a list to the more complex issues until you find out what is wrong
3 Reasons Why Your Toyota Corolla Engine Won’t Start
There are three primary reasons why your Toyota Corolla engine won’t start
- The engine won’t turn over
- There is no fuel or air delivered to the piston cylinders
- The spark plug is not firing
While there can be other issues, these three cover the most common reasons.
1. The Engine Won’t Turn Over
When you turn the key (or in keyless models, press the starter button) electrical energy is sent to the starter motor.
The starter motor turns the engine over. Without making it too complex, this results in the following sequence of events (gas powered engine.).
- The pistons move up in the chamber
- Air and fuel is released into the piston chamber.
- An electrical charge is sent to the spark plug – which sparks.
- The fuel and air ignite causing a little explosion.
- The air in the chamber expands and forces the piston down.
- The expanded air is released through the exhaust valve.
- The whole process starts again.
If the engine won’t turn over and start this process, it will generally be for the following reasons.
The Toyota Corolla Has A Dead Battery
If the battery has lost its charge, there will not be enough power to the starter motor. This means the engine won’t start turning and so the combustion cycle cannot start.
The reasons for a dead battery are as follows.
- A power consumer (Interior reading lights, headlights lights, Stereo or entertainment system) was left on while the vehicle was left alone.
- The car security system is faulty and is draining the battery.
- The battery has reached the end of its life and needs to be replaced.
- The alternator is not working properly and is not charging the battery.
Check out this article on what to do if the battery saver light illuminates.
Diagnosis And Solution
The easiest way to diagnose a faulty battery is to check the following.
- The starter motor turns over very slowly and may stop while you turn the key.
- Do the instrument lights turn on when your turn the key?
- With the ignition on switch the head lights on and see how bright they are.
If either of these do not function properly the battery is probably discharged,
On an emergency there are two things to try and get the Toyota Corolla going.
- Push start the car (how to push start a car – video)
- Jump start the car from another vehicle with a healthy battery (How to jump start a car – video)
If the car starts using either of these two methods this is confirmation that the battery is at fault.
If the battery warning light on the instrument panel displays, there is either a problem with the battery, or more likely the car’s electrical charging system (alternator or belts). It is essential that you have this checked out urgently.
The Toyota Has a Faulty Ignition Switch
If the ignition switch is damaged there will be no power sent to the starter motor.
A faulty ignition switch can generally be detected because when turned, the instrument panel remains blank, and no warnings lights are displayed.
A faulty ignition switch will normally provide some warning before it fails completely. As the switch wears down it will become increasingly difficult activate the ignition.
When this happens, it is a good practice to have the switch checked out before it finally fails.
The only way to repair this is to change the switch
The Toyota Corolla Has a Bad Starter
If the starter has failed it means the engine won’t turn over. Although starter motors are generally very reliable, they do ultimately wear down and will require servicing.
The signs that a starter motor has failed include the following.
- The dash board warning lights activates, but the engine does not crank.
- The starter motor emits a clicking sound but doesn’t turn.
- It sound like the starter motor is turning very slowly (which also happens with a flat battery)
- A whirring sound is emitted by the starter motor, but the engine doesn’t turn over.
In most instances a failed starter motor will need to be rebuilt by a qualified mechanic.
The Toyota Corolla Has a Faulty Security System
If your car has a security system, it may be defective. Another possibility is that the batteries in the key fob have gone flat.
There are three possible consequences of this.
- The key fob is “dead” and does not deactivate the system.
- The battery discharges when the car is not used.
- The starter motor is disabled by the system.
There are two possible solutions.
- Renew the key fob battery.
- Disable the security system (not easy) or to have it repaired.
2. There Is No Fuel Or Air Delivered To The Piston Cylinders
In this instance there is possibly a problem with the fuel system.
Cause
If there is not fuel being delivered, the starter motor will turn over freely, but the engine won’t start.
If you lift the vehicles hood and have someone turn the starter motor. If there is no smell of fuel it may be a sign that gas is not getting through.
The most common reasons for no fuel getting through to the engine are as follows.
- The gas tank is empty.
- The gas tank or fuel line have a leak.’
- The fuel pump is faulty.
- The fuel filter is blocked.
- Old and gummy gas.
- There is a problem with the carburetor or fuel injection system.
Diagnosis And Solution
Check the following to try and locate the problem.
- Switch the ignition on and check if the fuel gauge rises. If empty fill with gas and try again.
- Check under the car for signs of a gas leak. If you find a wet spot under the car, smell if it is gas. If gas, there is a leak in the system. In this instance have the car professionally checked out.
- You can see how to check for a faulty fuel filter in this article.
- Removing and replacing a fuel filter is a simple DIY job.
- If the Toyota Corolla has been unused for years, the gas may have become old and gummy. Drain the gas and refill the tank with fresh fuel.
- If none of these steps fix the problem, there may be an issue with the carburetor or fuel injection system. These need to be rectified by a trained professional.
3. The Spark Plug Is Not Firing
The 3rd part of the equation is to check if the re is a spark being delivered to the piston chamber. The spark is produced by a sparkplug on each cylinder (The Toyota Corolla has four).
The system sends an electrical current to a coil, which steps the voltage up and activates the spark plug. In older Toyota Corollas there was a single coil that was connected to a distributor. The coil activated and the distributors end the current to each spark plug in the correct sequence.
Modern Toyota Corollas have individual coils that are attached to each spark plug. The engine computer calculates both the timing of the sparks and the fuel injector timing. It does this by counting the pulses from the crankshaft and camshaft position sensors
Cause Of No Spark
There are essentially three reasons why a spark plug will not fire.
- The HT leads (spark plug wires)are damaged.
- The coil(s) are defective.
- The sparkplug if defective.
- The engine computer is faulty
Diagnosis and Fix
A problem with an HT lead or spark plug will generally manifest with the engine producing less power and/or it sounding “lumpy”
In a car with more than one cylinder (I.e. A modern Toyota Corolla) it is unlikely that all the spark plugs, or HT leads would fail simultaneously.
In this case these two components can be ruled out of your diagnosis.
This only leaves the engine computer or ignition box. In this instance you will need to get professional assistance.