It's quite frustrating when you turn the car ignition on, but it just clicks instead of turning off the engine. No matter how annoying the problem is, it's not uncommon. Fortunately, fixing this problem doesn't guarantee a lot of money either. You need to know the basics in order to solve auto-clicks problem when trying to start.

1.
A discharged battery

Parasitic drainage is a valid reason for having a dead battery in the morning. A dead battery means that the car will not start when the ignition key is turned on.

If you leave the headlights, interior lighting
or the radio on while you leave the car in the parking lot at night, the battery will be completely discharged in the morning. The only solution is to jump start the car for which you will need jumper cables and another car with a functioning battery.

2.
Low battery voltage

The problem of clicking sound when starting the car can occur when the battery is low in voltage. The battery voltage may be low if you forget to charge the battery in time, or if the battery loses its functionality for any reason.

Cold weather could also be another cause. The battery requires a lot of power to start the engine in extremely cold conditions.
In the event of a defective battery, you may need to replace it. Use a multi-meter or car battery analyzer to determine the actual condition.

3.
Loose battery terminals

Another problem related to the battery that could be responsible for auto clicks when starting. Loose clamps occur when they are not properly tightened after repair work. Another reason is deterioration in the contact between the terminals and connectors. Bad contacts mean that the battery cannot provide enough current for the engine to start.
Check the terminals to see if any of the connection components are corroded. If you find something, repair the damage or change the terminals.

4.
Bad starter and / or magnet

If you can hear the click even though the battery is fully charged, look into the magnet or starter. This motor turns the flywheel that is needed to start the motor and the magnet is the switch that locks this motor in place. If the magnet is broken, it will prevent the car from making a click.

If the problem is a stuck magnet and you can easily access it, try tapping it lightly with a hammer to resolve it. Ask a friend to turn on the ignition. Be careful not to touch the rotating parts of the starter. If the starter rotates during the tapping process, you may need to replace both the starter and magnet.
Diagnosing the starter and its magnet requires specialist knowledge. If you are new to auto mechanics, take your car to an auto repair shop.

5.
Ground wire problem

There is a ground wire between the body and the battery or engine. If for any reason it's bad, it will cut power to the battery, resulting in the engine not responding to the ignition command.

This is a common problem with auto-clicks, but it won't start. However, you can solve it without getting professional service. All you need is an external jumper cable.

Connect the cable to the negative terminal of the battery and to one of the clean grounding points on the motor. If this starts the engine, check the cable between the engine and the body for damage. By cleaning the contact surfaces, the associated components sometimes function normally.
If this ground wire has no visible corrosion, continue with the wire between the body and the battery. Clean the contact surfaces so hopefully it will work again.

6.
Defective power cable

There is a power cable between the starter and the ignition switch. If it is faulty or fails for any reason, the starter may not be able to send enough power to start the engine.

This problem is not as common as the others mentioned here. However, if all other parts are functional, this cable should be investigated. Get the car's wiring diagram and find out if everything works normally.

LAST WORDS

Battery problems are the main cause of auto-clicks on startup. The above reasons are the most common and you can solve them by following the suggestions. If you cannot pinpoint the cause, seek professional help to prevent further complications.
Source:
http://www.eliancars.com/2020/12/6-possible-causes-of-car-clicks-when.html#more
[img]https://1.bp..com/-yjto9uESRQE/X8748Kw6CYI/AAAAAAAADz8/sPCpPicIrcsPJyRvIqhRZZbSwXjDmvP4QCLcBGAsYHQ/s320/Man%2Bstarting%2Ba%2Bcar.jpg[/img]


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Very informative.

Thanks