The VAZ-2107 speedometer does not work: injector, reasons

02/28/2022 10,748 VAZ 2107

Author: Ivan Baranov

The driver can learn about the main operating parameters of the vehicle thanks to the dashboard. This device is equipped with basic sensors and indicators that indicate the operation of certain devices. One such device is the tachometer. For what reasons does the tachometer on a VAZ 2107 carburetor not work and how to replace the device - detailed instructions are described below.

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Design and purpose of the tachometer

The purpose of the VAZ tachometer is to visualize the readings of the crankshaft. The device shows how fast the crankshaft rotates per minute, these readings are also called engine speed. Structurally, the VAZ 2107 tachometer is a milliammeter connected in one housing to an electronic part; these elements are installed on a printed circuit board.

As for the principle of operation, it consists in measuring the frequency of pulse transmission in the primary circuit of the engine ignition system. With the power unit operating, during one revolution of the camshaft, the contacts on the breaker should close and open 4 times. Accordingly, with one revolution, 4 voltage and current pulses are formed in the electrical circuit. As the crankshaft speed increases, the pulse transmission frequency also increases, which, in turn, affects the deflection of the instrument needle.

Tachometer malfunctions

The VAZ 2107 can have two types of engines: carburetor and injection. The electrical circuit for connecting tachometers in these cars is different from each other, and they are not interchangeable. Therefore, troubleshooting related to tachometer failure will differ depending on the engine type.

On a carburetor engine, three wires come from the tachometer. Two wires are the power (plus and minus), and the third is connected to terminal K of the ignition coil. In order to find out what caused the failure, you need to get to the back of the instrument cluster and disconnect the terminals from the block that goes to the tachometer. Next, you will need three wires to connect the tachometer directly to the battery (plus and minus) and to the ignition coil (terminal K). You start the engine, and if under such conditions the tachometer does not work, then the problem will have to be looked for either in the ignition system or in the tachometer itself, and if the tachometer starts working, then the fault lies in the wiring that goes to the tachometer.
On the injection engine of a VAZ 2107 car, four wires go to the tachometer. Two wires are power (plus comes from the ignition switch, minus to the vehicle ground), the third wire goes to the input of the electronic control unit, and the fourth is connected to the crankshaft position sensor. The best way to determine malfunctions in the tachometer in this case is to carry out appropriate diagnostics. Then, using the error codes, you find out the reason for the failure. Without diagnostics, you can only check the condition of the contacts in the blocks included in the electrical circuit of the tachometer and, by replacing the crankshaft position sensor with a known good one, check its functionality.
The tachometer may malfunction if the insulation of high-voltage wires is broken or the ignition coil is faulty. In this case, interruptions in engine operation and “floating” speed are also possible. In addition to the wires and coil, it is necessary to check the condition and adjustment of the breaker contact and the capacitance of the capacitor on it (for carburetor sevens). Faulty wires and, as a result, unstable engine operation, cause the tachometer to “jump” on injection VAZ models.
Fuel system malfunction. The cause of interruptions in engine operation and jumps in the tachometer needle can be either low-quality fuel or problems in the injection system. On carburetor models, disassemble the carburetor and clean the jets. Most often, a “jumping” tachometer is the result of a clogged idle jet. The VAZ 2107 tachometer (injector) can “jump” if there are problems in the injection system. In this case, it is necessary to flush the injectors. To check and clean the injection system, you need a special stand and equipment. It is better to entrust such work to service station specialists.
Malfunction of the gas distribution mechanism. When the tachometer needle begins to “jump” at high speeds, the problem may be associated with a malfunctioning gas distribution mechanism. In this case, it is necessary to check the tension of the timing belt connecting the crankshaft to the camshaft.

Replacing the tachometer yourself

In conclusion, let us remind you that your vehicle is always on the move, service it on time, listen to any bells that can be easily eliminated at the stage of the problem. This is the only way you can save your money and precious time.

Ignition system

As mentioned earlier, the ignition system of the VAZ 2107 car and the tachometer needle are interconnected; they cannot exist without each other. And if the arrow twitches, and all the above tips did not help, you should pay attention to the condition of the ignition elements. First of all, inspect the wires for damage or lack of contacts.

It is quite possible that there is a break inside the device itself. The photo shows a wiring diagram, study it to get an idea of where the wires go and where they come from. If the power system has a carburetor and a classic ignition system is installed, then it is possible that a breakdown of the capacitor installed in the lower part of the distributor has occurred.

In most cases, the needle jumps if there is a malfunction in the ignition system. It is quite possible that the Hall sensor is malfunctioning. But in this case, unstable engine operation will be felt. If you have an injector, then you should check the condition of the engine speed sensor and all connecting wires.

Very often failures occur after the tachometer has been disassembled or replaced. If you have performed such actions, then you need to carefully check whether the device is installed correctly, is the connection made in accordance with the diagram, is the arrow at zero when the engine is stopped? It is worth noting that there is a toggle switch on the back of the device; it is designed to set the needle to zero.

But there are times when at idle the needle behaves quite well. But at speed, when the speedometer passes the mark of 80 or 100 km/h, the needle begins to twitch strongly. In this case, it is even possible that misfires may occur. This is a sign that there is a breakdown in the ignition switch and it needs to be replaced urgently. That's all that can be said about the device designed to measure crankshaft rotation speed.

Abstract on the topic “Types of instrument clusters 2107”)))))

Let's look at the general diagram of devices 151.3801

Until 1988, instrument cluster 15.3801 was used

You can find instruments for export cars with a different speedometer scale (with miles)

Tidy 35.3801 for Gazelle and Sable cars is very similar to it

There is a device for UAZ Patriot cars with a slightly different connection

In short, when replacing devices, you can install the wrong one, and something will not show. For injection 2107s of the last years of production there is a tuned electronic device Gamma GF 607 with a trip computer and a astronomical price

The device 110.3801 for UAZ-3162 is not at all similar to the devices 2107

Kind of a conclusion. Although the devices are outdated and prone to breaking, they are still quite informative. At that time, the VAZ-2107 was one of the cars stuffed with all sorts of sensors. At the moment, 2107 devices are subject to collective farm damage due to the “unfashionable” weak and green backlight in our time. People install ugly scales with transparent numbers, glue diode strips inside, not noticing the factory beauty of one of the few instrument clusters at that time (the instruments are combined into one unit and have curved glass to eliminate glare), which appeared in the 80s.

Electrical diagram of VAZ 21074

In VAZ 21074 cars, electrical energy is delivered to consumers using a single-wire circuit: the “positive” terminal of each electrical device is powered from a source, the “negative” terminal is connected to “ground,” i.e., connected to the vehicle body. This solution simplifies the repair of electrical equipment and slows down the corrosion process. All electrical appliances of the car are powered from the battery (with the engine off) or the generator (with the engine running).

The wiring diagram of the VAZ 21074 injector contains an ECM, an electric fuel pump, injectors, and engine control sensors

Wiring diagram VAZ 21074 injector

The injection versions of the “Seven” released from the factory assembly line have the following indices:

LADA 2107–20 - in accordance with the Euro-2 standard;
LADA 2107–71 - for the Chinese market;
LADA-21074–20 (Euro-2);
LADA-21074–30 (Euro-3).

The injection modifications of the VAZ 2107 and VAZ 21074 use an ECM (electronic engine control system), an electric fuel pump, injectors, control sensors and monitoring engine parameters. As a result, there was a need for additional under-hood and interior wiring. In addition, the VAZ 2107 and VAZ 21074 are equipped with an additional relay and fuse box located under the glove compartment. The additional unit is supplied with wiring that supplies:

fuses: main relay power circuits;
controller constant power supply circuits;
electric fuel pump relay circuits;

relay:

The main thing;

fuel pump;

electric fan;

diagnostic connector.

Additional fuse and relay block VAZ 2107 injector located under the glove compartment

Providing electricity

The G7 is responsible for providing consumers with electricity:

Battery voltage 12 V, capacity 55 Ah;
generator type G-222 or 37.3701;
voltage regulator Ya112V, which automatically maintains the voltage within 13.6–14.7 V.

Diagram of the power supply system for the VAZ 21074 injector includes a generator, battery and voltage regulator

Engine starting

The starting system in the VAZ 21074 is a starter and ignition switch powered from the battery. There are two relays in the starter circuit:

auxiliary, which supplies power to the starter terminals;
retractor, due to which the starter shaft engages with the flywheel.

The starting system in the VAZ 21074 is a battery-powered starter with a relay and an ignition switch.

Ignition system

In early versions of the seventh VAZ model, a contact ignition system was used, which included:

ignition coil;
distributor with contact breaker;
spark plug;
high voltage wiring.

The VAZ 21074 contact ignition system consists of a coil, distributor, spark plugs and high-voltage wires

In 1989, the so-called contactless ignition system appeared, the circuit of which included:

Spark plug.
Distributor.
Screen.
Hall Sensor.
Electronic switch.
Ignition coil.
Mounting block.
Relay block.
Key and ignition lock.

In 1989, a contactless ignition system appeared, to the circuit of which a Hall sensor and an electronic switch were added

“Sevens” with injection engines use a more modern ignition circuit. The operation of this circuit is based on the fact that signals from the sensors are sent to the ECU (electronic control unit), which, based on the received data, generates electrical impulses and transmits them to a special module. After this, the voltage increases to the required value and is supplied to the spark plugs through high-voltage cables.

In injection "sevens" the operation of the ignition system is controlled by the electronic control unit of the ECU

Outdoor Lighting

The external lighting system includes:

Block headlights with dimensions.
Illumination of the engine compartment.
Mounting block.
Glove compartment lighting.
Instrument lighting switch.
Rear lights with dimensions.
Illuminated numbers.
Exterior lamp switch.
External lighting indicator lamp (in the speedometer).
Ignition.

The VAZ 21074 external lighting connection diagram will help in troubleshooting headlights and tail lights

Auxiliary equipment

Auxiliary or additional electrical equipment of the VAZ 21074 includes:

electric motors: windshield washer;
windshield wiper;
heater fan;
radiator cooling fan;

cigarette lighter;

watch.

The connection diagram for windshield wipers uses:

Gearmotors.
ED headlight washer.
Mounting block.
Egnition lock.
Washer switch.

Windshield wiper motors drive a trapezoid that moves the wipers across the windshield

Classification by operating principle

Mechanical or electromechanical tachometers with direct drive. The revolutions are transmitted to the dial indicator through a flexible shaft, which, through a worm gear, receives rotation directly from the crankshaft or one of the transmission shafts. The operating principle of the indicator is based on the phenomenon of eddy current induction. The operation and design of a magnetic tachometer are extremely similar to the operating principle of a car speedometer. In modern cars, a similar tachometer design is not used.
Electric machine. A distinctive feature is the connection to a generator. It is used primarily on diesel engines, but for the purpose of unification, a device of this type can also be used on gasoline engines.
Electronic. The signal can be taken either from the ignition system or directly from the computer. Installed on gasoline and diesel internal combustion engines.

Design and principle of operation

Main components of electric machine and electronic tachometers:

measuring unit, or signal converter. It can be based on elements of analog circuitry or built using special microcircuits;
display unit with analogue or digital display of the number of revolutions;
auxiliary elements.

Connection diagram

When looking for the reason why the tachometer does not work, it is first of all important to understand the connection diagram and the type of signal. There are 3 typical connection schemes:

to a contactless ignition system (the tachometer wire is connected to the primary circuit of the ignition coil). The operating principle is based on measuring the frequency of voltage surges in the primary circuit of the ignition system. Calculating the ignition angle is impossible without focusing on the number of crankshaft revolutions, therefore the sparking frequency directly depends on the crankshaft rotation speed. On 4-cylinder internal combustion engines, a full revolution of the crankshaft corresponds to 2 voltage pulses in the primary circuit. Accordingly, the higher the crankshaft rotation speed, the greater the frequency of voltage surges;
connection to the contact ignition system. The operating principle and connection diagram are similar to the BSZ, but the design of the measuring unit will differ depending on the voltage of the input circuit;
connection to the engine ECU. The principle of operation is still based on recording voltage pulses in the primary circuit of the ignition system, but the signal to the tachometer comes from the engine control unit;
connection to the generator (the tachometer signal contact is connected to terminal W of the generator). The rotation of the generator pulley is carried out by a belt drive from the crankshaft, so the rotation speed of the generator rotor will always be proportional to the crankshaft speed. The change in the number of revolutions of the crankshaft can be calculated by constantly measuring the amount of EMF generated on the winding. According to its principle of operation, an electric machine tachometer resembles a regular one class=”aligncenter” width=”448″ height=”412″

Typical faults

If the mechanical tachometer on a car stops working, there is mechanical damage to any of the structural elements. A broken cable of a flexible shaft, wear of the worm gear elements, the appearance of backlashes, deformations - all these reasons can cause the engine speed indicator to fail.

What to pay attention to if the electronic tachometer does not work:

wiring integrity

In this case, it is important to check not only the signal wire, but also the ground and power supply of the instrument panel; quality of contacts. The presence of oxides and loose contact inside the chips may well cause the tachometer to fail; the integrity of the elements of the measuring unit, which are located behind the protective glass inside the dashboard. Among mechanical damage to transistors, burnout of microcircuits, tracks or swelling of resistors, the most common reason for a non-working tachometer is a violation of solder integrity

For example, on the Mitsubishi Padjero II, the appearance of microcracks in the soldering areas of the tachometer elements is a generally recognized disease.

Among mechanical damage to transistors, burnout of microcircuits, tracks or swelling of resistors, the most common reason for a non-working tachometer is a violation of solder integrity. For example, on the Mitsubishi Padjero II, the appearance of microcracks in the soldering areas of the tachometer elements is a generally recognized disease.

VAZ 2107 tachometer does not work

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Hello everyone, today I would like to talk about the possible reasons why the tachometer on a VAZ 2107 does not work. The tachometer on a car plays a very important role and therefore cannot be delayed and urgently repaired or, in extreme cases, replaced.

So, to begin with, you must understand that the VAZ 2107 has two types of engines, namely carburetor and injection. Accordingly, the tachometer connection diagram on these machines is different. Well, let's first look at the carburetor seven.

Tachometer on a VAZ 2107 carburetor engine

On the carburetor seven, three wires come out from the tachometer. Two wires are plus and minus (power) and the third wire is connected to the ignition coil. If the tachometer is out of order, then in order to understand the reason you need to get to the terminals that go to the tachometer and disconnect it.

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You will need three wires to connect the tachometer directly to the battery plus and minus, as well as to the ignition coil, terminal K. Then you need to start the engine and see if the tachometer does not work, then the fault must be looked for in the ignition system or in the tachometer itself.

But, if the tachometer works, then the problem is in the wiring that goes to the tachometer.

Tachometer on a VAZ 2107 injection engine

Above we looked at tachometer malfunctions on the carburetor seven, now it’s time for the injection one. On the injection seven, there are no longer three, but four wires going to the tachometer. The two wires are plus and minus, the plus comes from the ignition switch, and the minus goes to the ground of the car. The third wire goes to the input of the control unit. The fourth is connected to the crankshaft position sensor. The best option to determine the malfunction of the tachometer on the injection seven is diagnostics. In this case, using the error codes, you can determine the reason why the tachometer does not work. Well, without diagnostics you can only check the contacts on the blocks. It also happens that the tachometer needle starts to twitch, this is mainly due to the fact that the owners change the standard wiring to a more modern one. And given the fact that the resistance is different, such a nuisance appears. Well, that’s all for today, we have looked at the main reasons for the failure of the tachometer on the VAZ 2107 for now. January 21, 2022 753