The first car from the Zhiguli family equipped with a tachometer was the VAZ 2103. Neither 2101 nor 2102 had such a device. The tachometer is used to measure the crankshaft speed. It is a revolution counter, showing their number by deflecting the scale needle to a certain angle. The tachometer is also indispensable when setting up the carburetor - its indicators are taken into account when adjusting the idle speed and the quality of the fuel mixture.
Why does the speedometer break?
It is worth noting that in some cases it is not difficult to repair the speedometer yourself.
In others, you will need the help of specialists. Thus, oxidation of contacts is considered a fairly easy to fix fault. It is characterized by the “jumping” of the arrow, despite the fact that the speed of movement remains stable. The problem is resolved by cleaning the contacts.
The wires are frayed. This reason can be suspected by the chaotic movement of the needle when starting the engine. Meanwhile, experts note that sometimes the problem does not manifest itself for a long time. It can be identified using a tester.
Sensor failure. A speed control device whose performance is questioned is replaced with a known good one. If the speedometer begins to function normally after this procedure, then there is no point in further looking for damage. Often sensors become unusable after their housing is destroyed and water or dirt gets inside.
Connectors. They are located in the VAZ-2110 in a place where they are constantly exposed to dirt. As a result, the contact is broken and the speedometer needle moves chaotically. The connectors must be completely cleaned and the connection must be checked for reliability.
Often the speedometer also begins to malfunction due to shaft wear. In this situation, it will be possible to get rid of the problem only after completely replacing the above-mentioned part.
Purpose and principle of operation of the speedometer
The car speed meter kit consists of a speed sensor (DS), connecting wires, a mains fuse and an indicating device. On the “tens”, a dial speedometer is installed. It is located on the dashboard and is made in a single unit with other instruments and indicators. When the car is moving, the speedometer needle shows the true speed, and the odometer records the distance traveled. Readings are displayed either on the LCD display or on the drum counter.
On VAZ-2110 cars of the first production, a mechanical speedometer drive was used, made in the form of a cable in a metal braid with tetrahedrons on both sides. For fastening to the device and the drive device there were special union nuts. The torque from the secondary shaft of the gearbox was transmitted directly to the indicating device via a cable.
The VAZ-2110 electronic speedometer is installed on models with injection engines.
The operating principle of the device is based on the Hall effect. The signal from the DS is transmitted to the electronic control unit (ECU) and, converted, enters the input of the speedometer circuit. In addition, it is involved in the ignition system and fuel supply to the injectors. DS is an asynchronous generator excited by permanent magnets. The signal enters the ECU in the form of electrical impulses proportional to the speed of the vehicle. For example, while a car travels a distance of 1 km, about 6 thousand of them enter the control unit.
Speed under control
Speed under control
It would seem, why do we need a tachometer? To safely travel around your native expanses, a speedometer is quite enough. If you also look at road signs from time to time, the speedometer will help you save money when meeting with law enforcement officers. The tachometer informs about something almost abstract: how many times the crankshaft manages to turn around in a minute. Why and who needs such information?
First of all, the driver of a car with a forced engine. It requires strict control of revolutions - here all the power is hidden in a narrow range of speeds in each gear, and the tachometer helps determine the moment of transition to the next gear - without dips or twists.
There is also an aesthetic side to the matter. People decorate their car as best they can, and a catchy dial on the dashboard is fashionable. Not everyone thinks about what is hidden behind the instrument readings. Is this why remote tachometers, which are plentiful in stores, are sometimes distinguished by an enviable - up to 25-30% - disregard for the accuracy of readings. We don’t recommend dealing with such people - fortunately, there are honest devices, which we’ll talk about.
In terms of price-quality ratio, the best tachometers are standard ones. Their work is based on different principles.
How to check the speed sensor
After examining the contacts and wires for oxidation, contamination, damage, if they are not found, then it is necessary to check the sensor itself. There are reliable methods for determining the performance of a device.
How to check the DS for functionality? The procedure for determining the health of the sensor can be carried out using a portable oscilloscope. It measures the signal coming from the device and displays it.
Using this method, you can visually determine not only that the sensor is faulty, but also try to determine the cause of the failure. You can get an idea of the nature of the signal using a conventional multimeter.
For diagnostics, it is necessary to connect the sensor wires to the measuring device, and rotate the device itself, holding the core. You can fix the sensor in the screwdriver sleeve. Then a rectangular image should appear on the oscilloscope screen. After one rotation, six pulses should be shown. This is what the signal from a working sensor looks like.
What the oscilloscope shows
If the speedometer on an injection-type VAZ 2110 does not work, and a signal is sent to the device, then the complaint is most likely to the speed sensor drive. If the edges of the shaft are mechanically damaged, then the functionality of the system can be restored only after replacing the DS.
Important! The DS test can be performed without dismantling the device. If you lift the front wheel with a jack, then by rotating it you can get the same effect as using a screwdriver.
What do traffic rules say?
The Traffic Rules state that the owner of a car is obliged to monitor the serviceability of his car. According to paragraph 2.3.1, before setting off, the driver must conduct a technical inspection of the car and make sure that its condition meets the requirements of current regulations.
Driving with a faulty speedometer is strictly prohibited by law. For violation of this rule, part 1 of article 12.5 of the Code of Administrative Offenses of the Russian Federation provides for a fine of 500 rubles. In addition, without this element of the dashboard it is easy to violate the speed limit, which will lead to the imposition of another administrative penalty.
Signs and causes of DS problems
VAZ “tens” are equipped with pointer indicating devices, i.e. the speed is judged by the angle of its deflection. If, while driving, the speedometer needle jumps and jumps, lies at “zero” or shows values that do not correspond to the true ones, and the odometer does not record the distance traveled, then this indicates a breakdown of the DS.
This situation occurs due to contamination of the sensor contact block, since the primary device is located on the gearbox housing under the hood and is not protected from dirt. The pad may be exposed to oil vapors penetrating through damaged seals. This leads to loss of contact and, as a result, incorrect speedometer readings. Such a breakdown can occur both with sensors with a square connector and with a round one. The difference between them is that the former are used in Bosh systems, and the latter in January 4 and GM.
When the speed sensor fails, unstable engine idling is often observed, and fuel consumption also increases. In this case, the DS is replaced. When choosing a working sensor, it is advisable to choose a model that is identical to the old one. Preference is given to products whose pinouts are indicated in the form of “-”, “A” and “+” rather than a digital designation. This will help when repairing the device and measuring the output signal.
The DS drive rod must be metal, not plastic. Otherwise, the service life will be no more than six months. When purchasing a working device, check that it is complete, that there are no backlashes, and that there is a washer on the rod. Replacing the DS is carried out independently and does not cause any difficulties.
Device
The tachometer makes it possible to switch to another speed in time so that the engine operates in economical mode. A novice driver can focus on the position of the arrow. If it approaches the red zone, then you need to shift to a higher gear. In addition, the device is used to adjust the operation of the power unit at idle and control the crankshaft speed while driving (author of the video - Avto-Blogger.ru).
Analog tachometers are reliable and simple measuring instruments.
Their design includes the following elements:
- pointer arrow;
- graduated scale;
- an electromagnetic coil with a shielded winding;
- cable for transmitting information from the crankshaft.
The operation of the device is based on the electronic principle. The signal from the crankshaft is transmitted through wires to a microcircuit, thanks to which the needle moves along the dial. Information can be taken directly from the shaft, from the generator or from other power take-off shafts. In this case, the original signal is converted with a certain coefficient.
Speedometer Troubleshooting Options
Before troubleshooting, you need to find out exactly the reason why the speedometer on the VAZ 2112 does not work. There is a reliable and simple method for this. The check begins with the speed sensor and, in search of a breakdown, moves towards the speedometer.
You should make sure that all wires and devices are in good working order. To determine the presence of a signal, you can use a lamp to which wires are soldered. It can be easily connected to the vehicle's on-board network.
Check procedure:
- The first wire is connected to the negative terminal of the battery.
- The second simulates impulses, trying to touch contact “A” with a certain frequency.
- If the speedometer reacts - the arrow turns at a small angle - then this part of the electrical circuit is working.
- By touching the contacts all the way from the block to the device, you can determine where the break is located.
VAZ 2110 with injector
The latest VAZ 2110 models are equipped with injectors. The search for reasons why the speedometer on a VAZ 2110 8-valve injector does not work should begin by checking the speed sensor. This car has an electronic speedometer located on the dashboard of the car.
If the speedometer does not work on a VAZ 2110, then it is necessary to change the entire panel, since manufacturers produce the panel with all the built-in instruments only as an assembly.
Mechanics
The following diagram shows exactly how the speed sensor is designed.
Speed sensor for VAZ-2112
- 2110-3843010-13 – sensor;
- 2110-3843010-18 – sensor;
- 2108-3802820-10 – speedometer drive;
- 2101-3802718 – gasket;
- 2108-3802822 – drive housing;
- 2108-3802830 – sealing ring;
- 2108-3802834-20 – driven gear;
- 2108-3802833-20 – drive gear;
- 2101-3802717 – washer;
- 15896211 – M6 nut;
- 12601271 – wavy washer;
- 11500121 – pin M6x14.
Elements 1 and 2 are interchangeable.
Dismantling
To remove the sensor from the car, you need to disconnect its connector. The sensor housing is fixed near the CV joint - the desired point is shown by an arrow.
First step in dismantling
When the connector is disconnected, take a flat key “22” and unscrew the plastic nut. Then you can change the sensor or repair it.
What you need here is a flat key
To replace the sensor drive, use a “10” key to unscrew the M6 nut and remove it together with the washer. The drive housing is rocked from side to side - you need a 14mm spanner.
Causes of malfunction on a VAZ 2110 with a carburetor
In the “ten” with a carburetor, torque is transmitted from the gear in the gearbox (gearbox) through a flexible shaft to the speedometer mechanism. In most cases, it is the shaft that may be causing the problem.
Flexible drive in the shell is the main cause of speedometer malfunction
If the speedometer stops working, first check the mounting points of the flexible drive . Tighten the nuts. If even after tightening the speedometer does not work, then the shaft has probably broken or there has been a breakdown in the mechanism on the instrument panel. In this case, the flexible shaft must be replaced. You can do this type of repair yourself. When installing a new drive, avoid extreme bending. Incorrect installation of the shaft will lead to unpleasant knocking.
If everything is in order with the flexible shaft and the instrument panel mechanism, then the problem is in the gear. It is located inside the checkpoint. We recommend that such repairs be carried out at a service station.
Replacement of different types of DS VAZ 2110
Replacing the “ten” speed sensor will not be difficult for a car enthusiast and will take very little time. To do this, you need to perform a series of operations sequentially. Work begins with completely de-energizing the vehicle by disconnecting the negative terminal from the battery. After this, the latch is removed and the block is disconnected from the DS. The wires are moved to the side and fixed so that there is no break near the block.
Then, using a 22 or 21 key (depending on the type of sensor), unscrew it from the speedometer drive. If it is necessary to replace the device, then it must be unscrewed with a 10mm wrench and carefully removed from the gearbox housing. If the actuator rod falls into the gearbox, complete disassembly will be necessary.
After this, a working product is installed and the block is inserted. The numbering of the terminals on the DC and the harness chip must match. After completing the repair, you need to check the operation of the kit. If it will be done in a garage on hanging wheels, then you must remember to turn on the ignition.
On the VAZ-2110 of the first releases, a mechanical DS was installed, consisting of a cable, a speedometer and a drive. Replacing the latter is similar to that described above. It must be remembered that the sensors installed on the VAZ-2110 before 2006 differ in mounting and are not interchangeable.
Replacement features
The speedometer is located on the main instrument panel. And if, after checking all possible reasons why the device does not work, it turns out that all the faults lie in the device itself, then the entire panel will have to be replaced, and not just this individual element.
Today, unfortunately, spare parts for dashboards are not sold and this complicates the entire replacement process. It is worth noting that when installing a new device, you can rewind the mileage indicators.
You can read about the location of elements and indicators on the instrument panel here: https://vazweb.ru/desyatka/salon/schitok-priborov.html
Expert recommendations
Some expert recommendations regarding diagnostics and repair of speakers:
- Diagnosis of the cause of unit failure should begin with a visual inspection of the speed sensor, as well as the wiring connected to it. As practice shows, the reason often lies in a broken wiring, in particular, in the place next to the plug.
- If the controller is covered with dust or oil, you need to dismantle it and wipe it thoroughly. Then you can put the sensor in place and try to check the performance of the speaker. There is a possibility that after these steps the speaker will operate normally.
- Under no circumstances should you drive with a non-working speaker, so if problems are found in its operation and you cannot check it yourself, you need to seek help from a specialist.
Every measuring device has an error
This is an immutable rule of metrology. Absolutely every device can lie, not just the one located in the car. For example, any pilot will tell you that airplane instruments regularly do not show the truth, so they have to take into account various corrections to the instrument readings. Otherwise, pilots simply will not be able to be confident in the reality of the values.
Therefore, the question will not be whether the devices deceive people in principle, but what is their error? How important is this for the driver? Should this be taken into account? If yes, then how? Most people do not need abstruse formulas and diagrams, and those who still need it can easily find it on specialized sites
Any more or less attentive driver has noticed at least once that on trips, especially long ones, there are always inconsistencies. You can find a simple and understandable explanation for this, without unnecessary details that are of little interest to anyone, such as mathematical formulas and complex calculations based on them
However, first of all, we need to discuss a few points that are considered common to everyone.
