VAZ 2112 engine ignition coil - this is the main part of the car’s ignition system, which serves as a conventional low-voltage direct current converter, which comes from the battery or directly from the electric generator into high-voltage voltage for further supplying an electrical impulse to the spark plugs.
In today's article we will learn how to check the ignition module on an injection VAZ-2112 8 valve with our own hands, and also consider step-by-step instructions for replacing this car unit.
Purpose and design of the ignition coil of the VAZ 2112
To create a pulse (spark) between the electrodes of the spark plug of the VAZ 2112 carburetor engine, a “standard”, classic or case coil was used for a non-contact ignition system (BSI), which is a high-voltage pulse step-up transformer with an open or closed magnetic circuit. Its use on “two-wheelers” continued until it was replaced by a two-spark (four-terminal) ignition coil (module) for 8-valve injection engines and an individual coil for power units with 16 valves.
New ignition coil for VAZ 2112
Diagnostics of malfunctions of the VAZ 2112 housing ignition coil for BSZ, nomenclature number 3122.3705 or 8352.12, consists of measuring the resistance of its primary and secondary windings and comparing the obtained data with table values. The resistance of the primary winding of coil 3122.3705 should be 0.43 (±0.04) Ohm, the secondary winding - 4.08 (±0.4) kOhm. The resistance of the coil 8352.12 is respectively 0.42 (±0.05) Ohm and 5 (±1) kOhm. The insulation resistance to ground must be at least 50 MOhm.
If measurement results differ by more than tolerance values, the coil must be replaced. You need the VAZ 2112 ignition coil, with its relatively low price, it is quite reliable and its replacement is rather an exception to the rule.
Ignition module VAZ 2112
The ignition module (four-terminal coil) provides simultaneous sparking in two cylinders (the first and fourth or the second and third). It needs to be checked for serviceability if there is no spark on one or more spark plugs. It is checked using a stand that simulates various engine operating modes and an oscilloscope. Checking “in the field” consists of connecting a known working spark plug one by one to the tips of high-voltage wires, grounding it to ground and, turning the crankshaft with the starter, visually detecting spark formation on the electrodes of the “test” spark plug.
Checking for errors
VAZ 2114 engine mounts signs of malfunction
Checking the ignition device for malfunctions always concerns the location of the wires on the ignition module of the VAZ 2114. For simple diagnostics, we simply measure the resistance between the wires of the first and fourth cylinders and the second and third cylinders with a multimeter. If the indicator is 5.5 kOhm (switch the multimeter to ohmmeter mode!), then everything is in order. There are also other checks:
- The first thing to check is the wiring block; it is better to disconnect it and check it with a multimeter in voltmeter mode: we attach the multimeter probe to pin A, and throw the other one onto the ground of the sliders. We start and look at the voltmeter values: excellent. If the voltage fluctuates around 12 V. If there is no voltage, check the ignition coil fuse, it may blow, as well as the correct connection of all contacts. By the way, about that. Another way of checking can indicate that the circuit of contacts is closed incorrectly: by connecting a tester to both contacts - A and B - connect a multimeter to it; if it blinks, then the circuit is in perfect order.
- It’s worth checking all the high-voltage elements (with the same multimeter in ohmmeter mode); if they are installed incorrectly, the ignition coil will burn out.
- To understand whether the ignition module behaves correctly, move the wire block, you can knock on it. The contact should not disappear, if the engine responds to your movements, the contact is unclear. It can break at any moment.
Symptoms of an ignition coil malfunction are often displayed by the system during basic diagnostics in a service center (or in a garage environment via a connected laptop with a special program) in the form of errors:
- P0351 – break in the winding of wires of cylinders 1-4
- P0352 – break in the wire winding of cylinders 2-3
- P3000 (P3001 P3002 P3003 P3004) – the ignition does not work.
All these errors are motivation for a deeper diagnosis of the situation, on which the decision will depend: replace the module with a new one, or repair it. Also, these errors may indicate a possible malfunction of one of the spark plugs or an explosive contact.
Version of the module on the 8-valve VAZ-2112
Two 8-valve engines of different volumes were installed on the twelve-wheeler - 1.5 and 1.6 liters. The ignition modules for these engines are different. The one and a half liter engine has a module with article number 2112-3705010, and the 1600 cc engine is equipped with a module 2111-3705010. A module for a 1.5 liter engine costs about 1500-2100, and the second one is 500 rubles cheaper.
Which is better?
SOATE devices manufactured in Stary Oskol have proven themselves to be the most reliable ignition modules.
Module structure
It consists of two ignition coils and two high-voltage switch switches. The coils are designed to create high-voltage pulses.
In essence, it is a simple transformer that has two windings: a primary winding, with an induction voltage of approximately five hundred Volts, and a secondary winding, with an inductive voltage of at least twenty kiloVolts. Everything is placed in one housing with one connector for signal wires and four for high-voltage.
Structure of the ignition coil module of the VAZ 2112
The operation of the ignition module is based on the “idle spark principle”. The module is capable of distributing a spark in pairs: to the first and fourth, second and third cylinders when transmitting pulses from the electronic control unit.
Which is better?
SOATE devices manufactured in Stary Oskol have proven themselves to be the most reliable ignition modules.
Module structure
The module consists of two ignition coils and two high-voltage switch switches.
Inside the module there is a board with radio components and ignition coils filled with compound.
The coil generates a high voltage pulse, and it is a simple transformer with two windings, primary (induction voltage about 500 V) and secondary (induction voltage at least 20 kV). All this is assembled in a single housing, on which there is a connector for signal wires (from the engine control unit) and four terminals for high-voltage wires.
Schematic diagram of the module.
The module operates on the principle of an idle spark - it distributes sparks in pairs to cylinders 1-4 and 2-3 according to impulses transmitted from the ECU.
Malfunctions of ignition modules on VAZ-2112
The process of removing the ignition coil on a VAZ 2112
If the VAZ 2112 engine starts running intermittently or does not start at all, the cause of the problem may be the ignition module.
Characteristic symptoms of a malfunction of the ignition module of the VAZ 2110:
- insufficient engine power,
- when accelerating the car jerks,
- either 1 and 4 or 2 and 3 do not work at the same time,
- the engine does not start.
It should be noted that on the VAZ-2112 one of the coils is responsible for the operation of cylinders 1 and 4, the second - for cylinders 2 and 3. If one ignition coil fails inside the monolithic block, two cylinders stop working at once.
To eliminate all other components of the ignition system, make sure that the spark plugs are in working order.
Installation of a new ignition module for VAZ 2112
To do this, unscrew them and check the spark on each of the spark plugs by cranking the engine with the starter and placing the spark plug with the high-voltage wire on the head so that the body (threaded part) of the spark plug touches the engine mass.
If there is no spark or it is weak, replace the spark plug with one that is known to work. If this does not lead to anything, check the high-voltage wires.
Thus, we will exclude spark plugs, caps and high-voltage wires from the list of non-working elements. Next we will check the ignition module.
Ignition module: connection diagram
To diagnose and repair breakdowns, you need to understand which wires come from where and what they are responsible for. If the engine fails, is it the spark plugs or the switch? Again, let's look at the circuit using the example of the VAZ 2114, 2115 ignition modules.
On the body of the device there is a block with 4 contacts A,B,C,D (of course, modules from other cars have different markings, but the principle remains the same). Ground contact is the default; the design of the car allows all electronic modules to be connected by a negative bus. Power is supplied from a 12 volt bus, “RUN ON”, that is, it works after turning the ignition key (don’t forget about this when testing with a tester). The system is powered through a fuse, often shared with some other devices. Diagnosis of the ignition module begins with checking the fusible element.
Two main contacts: output to 1-4 candles, and 2-3 candles. It is to them that the control signal comes from the switch. The connections are straight, dialed through the contacts of the pads. The pad itself is quite flimsy and must be handled with care. The same cannot be said about power outputs for high-voltage wires.
Important! For safety reasons, it is recommended to disconnect the battery terminals before removing high-voltage wires. At least at this moment the ignition key should be in the "off" mode.
These contacts are directly connected to the working terminals of the spark plugs. Often the problem lies in high-voltage wires. It is enough to replace them, and repair of the ignition module will not be required.
By running your hand along these wires away from the spark plugs, you can easily determine where the ignition module is located. Of course, in the engine compartment, at a short distance from the cylinder block (extra length of the high-voltage cable reduces the reliability of the system). As a rule, removing the ignition module for diagnostics, repair or replacement does not require dismantling other components.
Removing and replacing the ignition coil
In order to replace the module (ignition coil) on a VAZ 2112, you must perform the following steps:
- Before starting work, be sure to disconnect the battery by disconnecting the “-” terminal from it. (How to de-energize a battery.
- Then, approaching the ignition coil, disconnect one single high-voltage wire from its central part.
- Next, use a wrench to remove the two side nuts that hold the ends of the wires in place on the side of the coil.
- Next, when the nuts are unscrewed, remove both side wires from the coil.
- And to complete the operation, unscrew the two side nuts securing the ignition coil itself to the bracket.
- And then remove the coil from the car engine.
How to check
Checking the VAZ 2114 ignition module begins with preparing the equipment. And the best diagnostician in this case would be a device for checking the ignition module such as an oscilloscope. Unfortunately, not every Russian driver has an idea of what it is, not to mention the ability to use it. Therefore, we focus on the end consumer and use available means:
- 12-volt light bulb or control in common parlance
- Tester, it can be purchased for pennies at any spare parts store
Before touching the module itself, pay attention to its accompanying parts. We start with the wire block, it’s worth disconnecting it and checking the voltage
To do this, we fix the tester terminal on contact A, and throw the other one onto the ground of the sliders. Normal voltage is 12 V. If it is not there, then the problem is clearly in the fuse. It's a different story with him. Next, along the wires: we throw the tester terminal onto contacts both A and B. We start, the starter starts, the control indicator should ideally blink. If this does not happen, then the problem is a break in the contact circuit A.
Now directly to the ignition module. There are several options for diagnosis:
- One of the simplest types of diagnostics is to replace a non-working unit with a working one. Of course, for this you need a “donor”. We replaced it, looked at it, and drew conclusions. The only thing that can be an obstacle is that you need an identical unit, that is, a friend with the same car of the same year as yours. Because for 1.5 engines it is the module that is used, and for 1.6 engines only a coil is used. And remember about the working explosive wires, if they fly, then the module is bent because of them. Again, checking BB contacts is a different story.
- You can do it differently - move the ignition unit. What does this mean: you need to shake the block with contacts, then hit the module and shake it. At this time, the engine itself must be running, because all these actions are necessary in order to see whether its operation will remain flawless when staggering. If not, then again take a closer look at the wiring.
- Another way: put the tester in the operating state of the ohmmeter. We measure the resistance on the explosive wires that go to cylinders 1 and 4. And then - to 2 and 3. The normal resistance is considered to be from 5.2 to 5.5 Ohms.
Important: the ignition module most often cannot be repaired. Or is the repair not worth it?
It's easier to buy a new one and install it.
You can buy an ignition module for a VAZ 2114 anywhere and anytime, the price is not that steep - from 2,000 to 4,000 thousand rubles, depending on the region and the quality of the unit (manufacturer, new or used). But, if you decide to get confused, then be sure to look at the information on how to check the serviceability of the ignition module.
If you still doubt your own abilities, the doors of the service are always open for you. Moreover, the ignition module itself can be of both domestic and foreign production. But, no matter how strange it may sound, a qualified mechanic will most likely use all of the above techniques for the process, because he knows how to check the ignition module on a VAZ 2114. With rare exceptions, you can find someone in the service who will use an oscilloscope. Therefore, ride it once and see how and what is being done. At least some benefit from the time and money spent is a clear example for independent garage diagnostics.
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Do-it-yourself installation of the VAZ 2112 ignition module
- Having picked up the new coil, first install it in its place by tightening the two nuts that secure it.
- Then place two wires on the sides of the coil and secure them with retaining nuts.
- When installing two side wires, pay attention to the markings that are marked on the sides of the ignition coil (see photo below). So this marking indicates which terminal of the coil should be connected to this or that wire. The blue wire must be connected to the “B” marking, and the red wire must be connected to the “K” marking!
- Then place the high-voltage wire on the central part of the ignition coil.
- And then install the negative terminal on the battery.
On old ignition coils, as a rule, instead of the letters “B” and “K”, the designations “-” and “+” are used, which means the same thing, but only in signs. The blue wire must be connected to the “-” sign, and the red wire must be connected to the “+” sign!
