Car diagnostics: how to check the ignition coil with a multimeter for operability
The technique is presented. How to check the ignition coil with a multimeter. The principle of operation, signs and causes of device malfunction are considered.
Purpose and device of the ignition coil
The ignition coil is necessary to create a high voltage in the car engine, which causes a spark in the spark plugs of the engine cylinders. This spark ignites the fuel.
Such a coil is a step-up pulse transformer consisting of two windings and a magnetic circuit. The primary winding of the coil is made up of a small amount of thick copper wire and the secondary winding is made up of a large amount of thin wire.
The principle of operation of the ignition coil is that when the primary circuit, powered by a low-voltage battery, is opened, a current pulse arises in it, due to which an electromotive force is induced in the secondary winding. The magnitude of the voltage arising there, due to the large transformation ratio, is many times higher than the supply voltage of the primary winding.
It reaches a value of 25-35 kV. High voltage is applied to the spark plugs where a spark is generated.
Car diagnostics: how to check the ignition coil with a multimeter for operability
The coil is an important element of the car ignition system. In the event of a malfunction, the vehicle may malfunction.
It is possible that the car, due to the engine stopping due to a malfunction of this coil, will not be able to move at all. Therefore, it is important for a motorist to know how to check the performance of the ignition coil.
Symptoms and causes of malfunction
When checking the performance of the ignition coil, it is possible to identify malfunctions according to the following signs:
- The car engine cannot be started;
- The dashboard shows an error;
- Misfiring occurs;
- Excessive heating of the coil.
The following reasons are possible due to which the coil has failed:
- Mechanical damage;
- Using low quality candles;
- Adverse effects of the external environment.
Mechanical damage to the coil can occur due to strong vibration or oil leakage. As a result, the integrity of the coil insulation may be compromised, which can lead to a breakdown.
It is convenient to check the LEDs for serviceability with the same multimeter. Read here how to do it correctly.
The use of substandard spark plugs can cause breakdown of the insulator and the formation of back gases, which have a negative effect on the rubber tip of the coil. Damage to the tip can cause high voltage breakdown to ground.
During vehicle operation, the coil may be affected by such factors as moisture, dust, dirt.
Choosing lawn mowers ignition together with specialists
Ignition coil for lawn mowers of different models, brands, like the entire magneto complex, including wires and attachments, will be different from each other. For example, a part intended for a Stihl braid will not necessarily fit Oleo-Mac, and it is better to stop your choice on original spare parts, most of which are presented in our catalog.
So, we propose to choose the ignition that interests many buyers of the "lawnmower network", guided by its following parameters:
Spare parts for lawn mowers can be roughly divided into main and auxiliary. One way or another, a magneto or an ignition coil is rightfully considered an element that will require immediate replacement if the tool breaks. Our experts will help you buy any of the existing samples for modern trimmers, they will also step by step describe the installation of a new part.
Replacing the ignition of lawn mowers
- We remove the plastic casing and on the left, above the rod, we will see the ignition module.
- A system malfunction can be diagnosed if even replacing the spark plug with a new one did not change the situation and the spark did not appear. There are also cases when a spark is present or occurs intermittently, but it is the ignition that is faulty. In the second case, the unit can start up, and after working for a few seconds it can overheat and no longer work.
- Unscrew the 2 screws that secure the module. Externally, its breakdown may consist in the departure of the elements of the part among themselves, gaps, tears, fractures.
- Before installing a new ignition, we turn the flywheel so that its metal elements look up, and you have seen them.
- We install the tool on the flywheel from above, which will help maintain the gap between the new coil and the flywheel, but at home you can use a regular calendar, business card or A4 sheet folded in four.
- Next, we mount a new ignition, bolting it into place.
- After it is firmly fixed, we take out the "calendar", connect the wires and put on the candle. Trying to start.
Ignition Coil for Husqvarna Lawn Mowers 143R "WIN.
Ignition Coil for Husqvarna Lawn Mowers 143R "WINZOR" Coil The ignition of the engine ignition system is an element of the ignition system that converts low voltage.
Trimmer ignition is one of the important elements in a similar gasoline scythe system, which provokes an electric spark that ignites the fuel and sets the entire mechanism in motion. This module sets a kind of push. The entire system consists of the ignition itself (or magneto) and the flywheel. The last element for the petrol trimmer is an aluminum part, it also serves as a fan. It has blades that drive air flows – the part cools the engine. Installed two plastic "pawls" with springs are designed to engage with the recoil starter.
How to check the ignition coil
One of the most important elements of the ignition system of any gasoline engine is the coil. It is she who is considered the main unit of contact, contactless, as well as electronic ignition systems, performing the role of a kind of energy storage device designed for further distribution of the charge over the cylinders.
Causes of coil malfunction
Partial damage to the ignition coil leads to unstable engine operation, and its complete breakdown completely makes it impossible to start the engine. That is why, when the engine is tripled, its power is lost or other signs of fuzzy operation, one of the first actions should be to check the ignition coil. This element fails quite rarely, and the malfunction, as a rule, consists in the following:
- Insulation damage due to strong heat, vibration or high voltage, which in turn leads to a short circuit in the coil windings;
- Overloading caused by faulty high voltage wires or spark plugs can break the coil winding.
Methods for checking the ignition coil
Checking the ignition coil by the "old-fashioned" method can damage the electrician of a modern car
For proper self-checking of this car part, it is recommended to perform certain actions in stages. First of all, after removing the coil, you need to visually inspect it and make sure that there are no external signs of a short circuit: black dots indicating burnout, cracks, or other signs of breakdown.
In our country, for a long time, there were two equally popular ways of how to check the ignition coil for performance: by checking the spark between the car body and the spark plug or by measuring the resistance of the windings with a multimeter (tester). The use of the first method can be fatal not only for the coil, but also for the electronics of most modern cars, therefore its use is strongly discouraged by manufacturers. It is safer to check this part of the car with a measuring device.
The principle of operation of the ignition coil
As mentioned above, the ignition coil is a step-up voltage transformer that converts the resulting 12 V voltage into a voltage of several kilovolts. Structurally, the coil consists of two windings – primary and secondary (respectively, low and high voltage). However, depending on the type of coil, the windings and their location are different.
Let’s start with the simplest common coil. There are 100.150 turns on the primary here. The winding is wound with insulated copper wire. Its ends are brought out to the coil body. The number of turns of the high voltage winding is 30.50 thousand (depending on the model). Naturally, the wire used here is of a much smaller diameter. The "minus" of the secondary winding is connected to the "minus" of the primary. And the "plus" is connected to the terminal on the cover. In this way, the resulting high voltage is removed.
To increase the magnetic field, the windings are wound around a metal core. In some cases, to avoid overheating, the winding and core are filled with transformer oil (it not only cools the system, but also acts as an insulator).
Now let’s move on to considering individual ignition coil. There are also two windings here, but the difference lies in their location. In particular, they are wound in reverse order. The primary winding is of an internal type and the secondary is of an external type.
Individual ignition coils are installed in electronic ignition systems. Therefore, their design is complicated. So, a diode is provided to cut off a significant current in the secondary winding. Also, a feature of the individual coil is the fact that the resulting high voltage goes not to the distributor (as in classical systems), but directly to the spark plugs. This was made possible by a design that included an insulated body, rod and spring.
Another type of coil – two-pin. It supplies voltage to two cylinders at once. There are several varieties of them. Typically, such coils are combined into one common unit, which is essentially a four-lead ignition coil.
Regardless of the type of ignition coil, their main technical parameter, which should be guided by when diagnosing, is the resistance of the windings. In particular, the resistance of the primary winding is usually in the range of 0.5. 3.5 Ohm, and the secondary – 6.15 kOhm (these values may differ for different coils, so it is better to find reference information for the exact model used in your car). Measurements are made using traditional instruments – multimeters or ohmmeters. If the value obtained is very different from the specified, then there is a high probability that the coil is out of order.
You also need to be aware of the fact that each coil has different indicators:
- Winding resistance;
- Spark duration;
- Spark energy;
- Spark current;
- Primary inductance.
Therefore, in order to understand how the coil readings correspond to the norm, it is necessary to clarify the technical characteristics of your individual coil. This is especially useful if the spark is missing, since the ignition coil is one of the first parts of the system to be checked.
Causes of malfunctions
There are several reasons due to which the ignition coil completely or partially fails. Among them:
- Mechanical damage. This can be trivial aging, due to which the destruction of insulation occurs. There is also the possibility of oil leaking through the seals, which gets on the insulation or coil body and destroys them. Repair in this case is hardly possible, so a complete replacement of the assembly would be the best option.
- Contact connection damage. In warm weather, this may be due to moisture entering the engine compartment. For example, during heavy rain, driving through deep puddles, car wash. In winter, it is likely that the composition sprinkled on the surface of the road to combat icing is likely to hit the coil.
- Overheat. Individual coils are often subject to it. Overheating can significantly reduce the life of the ignition coils. Overheating is difficult to control, but try to use good quality coolant and keep the engine cooling system working properly.
- Vibrations. They are especially detrimental to individual ignition coils. Vibration typically comes from the cylinder head (cylinder head). To reduce the number and amplitude of vibrations, make sure that the engine runs in normal mode (no detonation and with serviceable airbags).
Ignition coils are fairly reliable and durable units, and their failure is most often associated with aging and / or insulation breakdown. Next, we will consider methods for diagnosing coils.
Breakdown of the ignition coil
The ignition coil is designed to create a high voltage, which is then used by the spark plug. Therefore, its proper operation is necessary for the normal functioning of the ignition system. In fact, the coil is a small transformer, to the primary winding of which comes standard 12 V from the battery, and a voltage of several kV comes out. It is used in all ignition systems – contact, contactless and electronic. The reasons for coil failure are typical. As a rule, this is a wire break, insulation damage, mechanical deformation. Next, we will look at the symptoms of a malfunction and methods for diagnosing the ignition coil.
Replacing breaker contacts
After disassembling the magneto, it is necessary to remove the old breaker contacts and install the new ones correctly. To do this, you must:
- Move the latch, remove the cover from the breaker;
- Unscrew the screw holding the connecting conductor;
- Remove the screw securing the breaker plate to the magneto cover and remove it;
- Get the screw securing the breaker spring;
- Remove the lock washer from the axle, and then the lever with the cushion assembly, which it holds;
- Unscrew the screw securing the contact post, remove the part from the axle.
Assemble the assembly with new contacts in the reverse order.
Often, breakdowns of the ignition coils are associated with a short circuit or breakage of the windings and mechanical damage to the magneto case. This is due to strong shocks, liquid ingress and oxidation, and overheating.. If you avoid such incidents, you do not have to worry about the integrity of the ignition coil.
One of the magneto assemblies that regularly suffer from use are the high voltage wires through which the spark plugs receive current from the ignition module. They have a long service life, but they are damaged by the users themselves by careless handling when replacing candles, inadvertently pulling on the wire itself, and not on the tip. Another problem that can happen to them is moisture ingress and oxidation or damage to the insulation. By carefully pulling out the spark plug and avoiding liquid penetration into the instrument, these problems can be avoided.
So, the repair of the ignition coil is not very difficult and can be carried out by the user independently, but subject to the above procedure for disassembling and replacing the magneto or breaker contacts.
Before starting to diagnose magneto, you need to make sure that the problem is actually in this node. To do this, you need to check the entire chain and make sure that there are no other reasons for the breakage of the trimmer.
- First, you should carefully inspect the coil for cracks and other external defects on the case. Next, you need to examine all the elements and nodes that conduct current, and make sure that they are clean.
- The next step is to inspect the high voltage wires. They must be in good working order and securely attached to the contacts, free from rust and with intact insulation.
- The next step is to check the plug cap. As a result of careless actions, the user often tears it off the high-voltage wire, and then improvises and creates a homemade mount. You need to understand that any poor-quality connection in this place significantly reduces the power of the electric arc of the candle.
- Then you should make sure that the candle itself is in good working order. Filling the mower with poor quality gasoline will significantly reduce the life of this part. In addition, it may be flooded or have a large carbon deposit that interferes with operation. Sometimes the candle even sticks and doesn’t twist off.
- Next, you need to inspect the circuit breaker. On trimmers and chainsaws made in China, it often breaks.
After completing all these steps and excluding the listed nodes from the list of possible causes of failure, you should proceed to checking the coil. This can be done in several ways.