My car does not start and has a battery

The car does not start but if the lights of the board are turned on. Mechanical girl explains in simple steps how to know the fault.

My car does not start but if the lights turn on

Many times we turn off our car to put gasoline, or to do some other diligence and when we go to start it again, our car drives, but does not start. It is there when the question jumps. What will it be? Why does not the engine start?

We try to start the engine, the boot gives turns to it, but fails to start.

This is why today I am writing this article so that you can do various tests that help you to know what our car has and why it does not start:

As I always tell you, always things are discarded from the simplest to the most complex.

If when passing the switch to the ON position, the indicator lights turn on, at least we know that it has a battery.

Now we try to start it, if it has a very good battery, it should spin the motor at a good speed. If during this process the engine does not turn, it is possible that our battery is defective. That is, the battery has charge to turn on the lights, but not enough to start the engine.

What will be checked when the car does not start is the following:

1) Check if the gas pump starts.

2) Check if there is fuel pressure and it reaches the injectors flute.

3) Check if there is a spark towards the spark plugs.

4) Check if there are negative pulses in the injectors.

Now I explain the procedures:

1) Check if the gas pump starts.

This procedure is quite simple, just enough to lift the back seat of the car (for most of the cars is there) or where is our gas tank and just listen.

For this test, the safest thing is that it requires the help of another person, in such a way that one of them passes the ignition key to ON and the other listens closely to the operation of the pump. It is a short duration buzz, which serves to put pressure on the system.

Important to clarify that once the system loads, it will not turn on the pump again, it does not matter if you put the suiche back in ON position. In that case, we have to wait about 5 minutes.

2) Check if there is fuel pressure and it reaches the injectors flute.

Once we know that the gas pump ignites, we must verify if it reaches the injectors, this is done by looking for the pressure tap that exists in all the cars, this pressure outlet looks like the air intakes of the rubbers or of a bicycle


With a wrench or spade screwdriver, try pressing the center pin to release the valve and see if pressure comes out. You have to get good pressure afterwards if you already charge the system with the pump, otherwise it is possible that this is blocked the gasoline filter or have some leak of gasoline by some hose.

presion de gasolina

Check hose and fuel filter connections.

Many times it happens that people forget to change these filters. They are used to just making oil changes, but not air filter or gasoline. Hahaha.

3) Check if there is a spark towards the spark plugs.

To check for a spark is a simple job, but you have to be very careful about the following:

1.- Very high voltage is generated, around 40,000 V at 60,000 V. It is very little current, but it produces involuntary spasms that can cause accidental injuries besides being painful.

2.- In the modern cars if a spark jumps to some control cable that goes for example to the injectors, temperature sensor, oil pressure, among others, this spark will go to the computer completely damaging the microprocessor. So you have to be very careful with this test.

Colocar bujia

The test is simply to remove some of the spark plug wires from our engine and connect it to an old spark plug in good condition. The threaded part of the spark plug will connect it to some metal part of the engine that we know is firmly grounded.


Start the engine and verify that the spark in the spark plug is indeed visible. If there is no spark, we have a coil fault or power failure.

bujia a tierra

We must review in this case:

- Motor fuses.

- Electric connection.

- State of the internal winding in search of shorts in it.

4) Check if there are negative pulses in the injectors.

If we have fuel and we get to the engine, we have sparks in the spark plugs we just need the injectors to supply the gas to our cylinders. I already explained the procedure to know if there is an injection pulse.

First of all, we prove that there is positive voltage in the injectors.

You must assemble the LED bulb tester as indicated in the following article and then connect the negative tip to ground and the positive tip to either of the two terminals of the injector. Important that the injector is connected to its connector.

prueba con led alimentacion del inyector

The tester, when passing the suiche to the ON position, should turn on. It does not matter which of them you connect to. More information about what happens in my pulse test article.

If it does not turn on we have problems with the motor or injectors' fuse, it is usually 15A. Or also the main relay.

Let's test if a negative injection pulse arrives.


This is the pulse that the computer handles, then you have to check if it is sending it. To do this, connect the pulse tester that we used before, but this time the positive terminal is connected to the battery and the negative is connected to the negative of the injector. Do not know how to look for it? Read the following article.

prueba pulso negativo inyector con led

Start the motor and see if the led lights intermittently indicating the existence of the pulse.

If you do not turn on the led with this test, we may have:

1.- Some anti-theft system in the computer.

2.- The CKP sensor is damaged.

3.- Damaged branch.

Important Considerations in the realization of these tests:

Take care when possible not to make a short circuit in the injectors. When connecting the wires try to do it comfortably and that metal parts are far away or at a safe distance from the connection.

For the test of the coil, try to do it with an old spark plug and that it is well terrified in its base. Do not touch the metal part because the energy will be discharged on you.

Also try to get the spark generated away from the control cables to avoid further damage to the vehicle's computer.

Well, it's all for the moment.

Below is a video of how you perform these tests.


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Written by

Dennis García

Chica Mecánica



Muy buen trabajo

Dennis como siempre hasta con articulo. Chevere.

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    My car does not start and has a battery

    My car does not start and has a battery

    The car does not start but if the lights of the board are turned on. Mechanical girl explains in simple steps how to know the fault.

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    • Asked by Rafael
      on 04/12/2019
      Porfavor hagan tutoriales hacerca de las Chery Tiggo mod 2012 yo tengo una y no encuentro tutoriales para cambiar la pastilla de freno y cómo remplazar el bulbo de freno Answer:
      Rafael, cuando tenga una a disposición haré. : )

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