Ignition coil VAZ 2112: how to check and replace the ignition module with your own hands

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.

Connection diagram

The ignition module is part of the space under the hood, it’s easier to find it by the position of the high voltages, they go from the spark plugs straight to it.

Ignition coil diagram:

VAZ 2114 ignition coil diagram

This diagram is good to follow when you have to replace the ignition coil of a VAZ 2114. In principle, everything is transparent: from contacts with the controller (ECU) to high-voltage wires. The name of the circuit is often common under the name ignition coil pinout: the pinout is a visual representation of the functionality of the device's contacts, which are numbered according to their purpose.

It can be connected in two different ways: when the ignition system coil is removed and when it is directly in its place in the car engine.

If you are holding the module in front of you:

Let us recall the diagram: the first and fourth contacts are on one winding, the second and third – on the other (they are numbered in the diagram!)
Then, the lower explosive contact (left) goes to the first cylinder
On the second - upper explosive contact (left)
The third cylinder goes to the upper explosive contact (right)
On the fourth – lower explosive contact (right)

If the module is plugged into the engine, then pinouting the explosive contacts will be more difficult, because the device stands at an angle (as if in a diamond):

We throw the central lower contact onto the first cylinder
On the second - left contact
We put the upper contact on the third cylinder
On the fourth - right contact

Of course, the first installation option is more convenient, especially since the explosive wires require increased care in the nature of the connection (mixed up and won’t start, in the worst case, the entire engine system is ruined). Speaking to the point, it is clear that the connection diagram for the VAZ 2114 ignition module is not complicated.

By the way, buying an ignition coil is not a cheap pleasure; the price of an ignition module for a VAZ 2114 ranges from seven hundred to a thousand rubles, depending on the location of your city on the map of our country (for more information about how much an ignition module for a VAZ 2114 costs, you can find out by calling a disassembly service or a spare parts store, the running part is almost always in stock).

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.

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.

Methods for diagnosing device performance

The simplest method that will help determine the performance of the coil is to replace it with a similar working device. This is possible if there is somewhere to get it. Please note that the module must match the parameters of the device under test . If the engine with a working coil works as before the breakdown, the ignition module is definitely faulty.

The main testing method involves using a multimeter. It consists in determining the resistance of the secondary windings of the coils built into the ignition module. The method is simple and does not require additional skills. The device does not need to be removed for testing. The check is done with the engine turned off.

This is how you check the resistance of the secondary winding with a multimeter

High-voltage wires are removed from the module sockets.
The tester switch is set to the 20 kOhm position.
The multimeter rods are placed in turn in the recesses of the corresponding contact pairs (1 and 4, 2 and 3).
With an intact secondary winding, the performance in both cases is the same. Normally, the resistance should be about 5.4 kOhm (in some models the indicators differ, which needs to be clarified). If the resistance is much greater, then there is a winding break. The resistance is much lower - a breakdown. The coil is faulty and cannot be repaired.

Video: How to check the secondary winding with a multimeter

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.

Repair

So, for the VAZ 2110 the most common problem is the disappearance of voltage on cylinders 2 and 3. After some time, the engine starts working normally again if you press the rear plate of the module.

You should not put up with such a situation; it is better to immediately check the functionality of the unit, restore or replace it completely.

Removing the module

The procedure is quite simple.

Disconnect the negative cable from the battery.
Remove the plastic cover that covers the motor.
Remove the wires from the spark plugs.
Disconnect the wires from the ignition module. Their numbering is indicated on special white rings. And the cylinder number is indicated on the ignition module housing.
Disconnect the connector from the ignition module.
Using a 10mm socket, unscrew the three nuts that hold the block we are looking for.
Carefully remove it, after which you can begin further work.

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!