How To Test Car Starter

How To Test Car Starter

test car starter

It happens that the starter fails to switch on a car engine even when the battery of the car is in perfectly good condition. In such cases, the fault could be a mechanical one or it could be an electrical malfunction in the circuitry.

The starter system is pretty straightforward, checks are quite easy to make, you either need a test lamp, circuit tester or a voltmeter. Since a mechanical check only involves the checking of the pinion gear, you just need a spanner to do it.

Before we go to the first steps, let’s talk about the setups.

mzwmotor.com test car starter setups

First, the connection of the live terminal of the battery to a terminal on the switch of the solenoid is done via a heavy lead. The switch of the solenoid operates when the ignition is switched on. Meanwhile, the second terminal of the solenoid must be connected to one of the terminals of the starter motor. Another terminal of the motor is to be earthed either with a strap of wire put through the engine or with a gearbox.

The car’s bodywork is to be connected back to the earth terminal of the battery. The modern cars today come with a pre-engaged starter in which the solenoid is mounted on top of the casing. Older cars used to come with inertia starter where the solenoid was mounted separately in the compartment of the engine.

Find out what you can do with your car, here is what you need to do.

Step 1 – Check the starter pinion:

mzwmotor.com test car starter pinion

First, you should do is to switch on the headlights and give the starter a turn. Dim headlights indicate that the starter pinion has been jammed with the flywheel in a mesh.

Look for a square stub towards the end of the spindle of the starter motor. If you find one, use a spanner to turn it and consequently free the opinion. Make sure that you do not work on the starter switch unless you get the pinion freed first.

In the event where your car is a manual transmission vehicle, you need to switch off the ignition, put the car into the second gear and let go of the handbrake. The car will start to rock backward and forwards until the pinion is freed.

This case where the headlights are still bright as they were before, you will have to search for an electrical problem.

Step 2 – Finding the electrical fault:

electrical fault

The reason for electrical fault can be so many. The first thing you should do is the power input test, to test if the current reaches the solenoid or not. To do this, you have to connect a tester lamp between the earth and the feed terminal.

However, first, you will have to check the terminal of the battery and the battery itself. After that, check the second end of the earth strap of the battery. Next, with the help of a test lamp, or a circuit tester, find out if current reaches the solenoid or not.

Connect one of the leads, and the other is to be earthed to the bare metal of the bodywork. If the lamp lights up, the fault exists either in the starter or in the solenoid.

In such case where the lamp lights up when the connection is earthed to the body but fails to light up then it means that the earth strap of the engine is faulty. There might be a loose bolt and dirt might have caused a hindrance thus, leading to bad contact. If the lamp lights, when you earth it to the body but fails to light when it is earthed to the engine, then it means that the fault lies in the engine’s earth strap.

It may have a loose bolt with dirt underneath it, causing bad contact. However, if the lamp fails to light at all, then the connections between the solenoid and the battery are faulty. If this happens then you will have to do a power output test. The purpose of this test is to check the solenoid-to-starter current.

To do this, connect the test lamp between the earth and the output terminal of the solenoid.

Step 3 – Check the solenoid:

starter motor and solenoid structure

In order to check the functionality of the solenoid, you need a helper. Ask the helper to work on the starter switch, while you listen to the sound it makes. If the solenoid is working, you will hear ‘click’ sound which is made when the contacts close.

However, if you do not hear the mentioned ‘click’ sound then the fault might either in the switch of the ignition, the terminals of the ignition switch, in the solenoid itself or in the wiring.

Step 4 – check the wiring of the ignition switch:

ignition switch & key

In order to make sure that the solenoid delivers proper current to the motor of the starter, connect the lamp between the battery earth and solenoid that leads to the starter. When the connection is not faulty then the lamp should light up when the starter switch is worked. In the case where the lamp fails to light up, put the car on the parking, then put the car in neutral gear.

The next step is to switch off the ignition and then carefully bridge the two primary terminals present on the solenoid.  In this way, the switch contacts present within the solenoid will be bypassed. Then, by using a strong screwdriver that comes with an insulated handle, peel the covers of the rubber terminal and jam the blade between the terminal for a few seconds.

Make sure that your hands do not make contact with the blade. Doing this would cause a spark and the starter might turn. It the starter turns, it is an indication that the problem lies in the solenoid. If the starter does not turn, then the starter motor is faulty. In such a case, the car has to be sent for repair.

Testing the car starter with a voltmeter:

mzwmotor.com voltmeterThe reason that voltmeter is much more easily accessible for you, then the process of checking the starter differs a bit. The initial process of testing the starter is the same.

You need to switch the headlights on and then give the starter a try. If the headlights appear dim, then you will have to check the terminal of the starter pinion, the starter pinion itself, and the earth strap. If you think that the battery sound, then uses voltmeter in the following way.

Step #1 – disconnect engine:

The first thing you need to do is to prevent the starting of the engine. To do this, disconnect the feed wire connected to the coil. This mark will either be a + sign or with SW.

Step #2 – check the battery:

car battery

You have to connect the leads of the voltmeter across the terminals of the battery. The reading of the dial should be more than 12 volts. Afterward, you need to work the starter switch. The reading on the dial will fall but it should not go below 10.5 volts. If the reading stays constant, then it means that the fault exists either in the solenoid or in the ignition switch circuit. If the starter either turns slowly or doesn’t turn at all and the reading goes below 10.5 volts, then this is an indication of a flat battery.

On the other hand, if the reading is between 10.5 and 12 volts and the starter slowly turns then there is either high resistance in the circuit or a mechanical seizure in the engine or the starter which causes its inability to turn freely.

Step #3 – check the starter:

car starter system

Finally, the last step is to check the voltage that is reaching the starter. When your car has a negative earth system, then you should connect the positive end of the voltmeter to the solenoid’s feed terminal. If the system is positive earth one, the leads of the voltmeter have to reverse. The starter is an inertia type, then the positive lead is to be connected to the starter motor’s feed terminal.

Now, touch the negative lead of the voltmeter to the bare metal of the motor. Second, the voltage will drop not more than 0.5V. If the reading stays above 10.5V, this means that the starter circuit is perfectly fine and the problem lies in either the engine, motor, or in the solenoid.

However, if the voltage drops very steep then this indicates high resistance within the starter circuit. Next, connect the battery live terminal in voltmeter negative lead and the starter motor’s feed terminal to the positive lead. The reading on the voltmeter should be 12V and it should reduce by 0.5V when the starter switch worked. If the voltage does not fall, then check the solenoid.

So, there you have it, all the ways to test car starter. If you have any question don’t hesitate to comment below and we surely answer that!

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