Both in principle of operation and in maintenance, gasoline and diesel engines are different from each other. This can be immediately seen by looking under the hood of the car or by pressing the accelerator pedal a couple of times. The devices installed in the car have the same functionality and appearance, but the connection in some cases is different.
No less important on the topic under discussion is such a factor as: where to connect the tachometer. Further consideration can be divided into two parts.
Connecting to the car to diesel
To connect a tachometer to a diesel engine, you need to get close to the generator coil. In most cases, you need to go to the inspection hole, remove the protection of the generator, having cleaned it of dirt. On the generator coil itself there are terminals, each responsible for a separate process. We find the terminal with the inscription "W". Here it is necessary to connect the contact from the tachometer to this terminal. In order for the correctness of his testimony to be true, we take and close the contact that departs from the high pressure oil pump. Otherwise, after reaching 2500 rpm, the light on the dashboard will light up, which is responsible for the oil pressure in the system. And I completely forgot, in a number of cases, after opening the generator cover, car owners do not find the terminal with the inscription “W”, sinning against the manufacturer, who did not see the need for this. When this is the case, you need to make out on the winding the output of contacts to the built-in rectifier of the generator, there will be three of them. Solder the end of the tachometer cable to one of them. If all actions are correct, the tachometer will work. After all the manipulations done, tighten the generator cover, make sure that the wire does not touch moving parts.
Connecting to a car with a gasoline engine
To correctly connect the tachometer to a car with a gasoline engine, the electrical diagram that comes with the device can help you. If there is no such scheme, do not be discouraged, everything is very simple and does not require the intervention of specialists. First, we fix the tachometer to the place where it will be convenient for you. There are three wires coming from the device itself. Black is ground, we connect it to the car body, Red is power, we connect it to the terminal on the ignition switch, to which a voltage of 12 volts is supplied from the generator or battery when turned on. The remaining wire, relative to the brand of the device, can have any color, we connect it depending on the ignition scheme. With a contact circuit, the tachometer is connected to the distributor breaker. If the ignition circuit is non-contact, then to the voltage switch. Almost all tachometers have a dial backlight, which must be connected to the parking lights of the car. To do this, we find the corresponding terminal on the ignition switch.
Here is the answer to the question of how to connect a tachometer. Happy connection!
Well, there is no tachometer in my car, no! Perhaps the Japanese thought that 86 horsepower is a little power for a car weighing 840 kg, and therefore a tachometer is not needed, or maybe they just made it cheaper. In vain they are. A tachometer is very necessary, especially if the gearbox is mechanical. Even if the driver is not racing. This minor misunderstanding is not easy to fix, but very simple. To do this, you need to buy the simplest digital tachometer and connect three wires to the correct places.
Let me tell you straight away, I'm talking about right hand drive. Toyota Corolla II with a 4E-FE engine, 1.3 in the back of an EL-51. I found two ways to connect: through the diagnostic connector, which is located under the hood; directly to the computer, aka ECU. For myself, I chose the second method. Its advantage is that you do not need to pull the already short and thin wires of the tachometer into the engine compartment, and at the time of installation it was raining outside, which, frankly, became the decisive factor in choosing the connection method. So, let's install the tachometer. First, let's find the place where the computer is located, it is also the brain of the car. It is located behind the glove box. To get to the treasured box, the glove compartment does not need to be removed. It is enough to squeeze him firmly on the sides and he will voluntarily tell you everything and give you access.
Now we need to decide where exactly to place the electronic tachometer board itself. I decided to put it next to the regular clock. And you don’t need to build up the wires, and you don’t need to make an extra hole, and you can see it well from the driver’s seat.
Now I will tell you how I fitted the wires. The digital tachometer has three wires: red (power "+"), gray (power "-") and white - signal. "Minus" we cling to the mass - it can be clamped with the nearest bolt. "Plus" and the signal connected to the computer through a chip-connector (the chip is marked in red).
Of course, before connecting the wires, I studied the pinout of the connectors and found where the necessary wires are located. Now I'll tell you this secret too... Of course, before removing the chip from the computer, you need to remove the positive terminal from the battery, but you understand that it's raining outside, don't you? Well, okay ... Here's the trick, the two correct wires are fenced off with my index finger.
Black is signal, green is positive. The task can be said to be solved. It remains to decide how to pick up the wires. Again, there are two options! The first is to remove the insulation and twist the wires. You can also secure it with electrical tape. But, as you already understood, I prefer the second method. Its essence is to pull the terminal out of the chip, slightly open the terminal mount and press our wire into it. It's great, right? Now try to get the terminal out of the chip. Dudki!! Either break the chip, or tear off the wire. But the Japanese are not stupid. However, like us, Russians, we are also not behind the Eastern brothers in mind (in some areas). The chip is reusable and disassembled. Look closely at both photos. Feel the difference?
Yes, this "panel" rises. But even after that, the terminals do not fall out in batches from the chip. It is necessary to gently press with a blunt awl on the plastic fastening of the desired terminal inside the connector itself. 
And only after that the terminal lends itself. Do you think I'm so smart that I immediately finished all this? No. This is me so stubborn. I turned the chip in my hands and pulled the terminals for about forty minutes. So, the clamp is free! Carefully use a knife to push the metal fasteners of the wire and push the desired wire. It turns out something like this:
After that, I clamp everything “backward” with pliers. I put the clamp in place. I do the same for the second wire:
I “assemble” the chip, “press in” the magic socket, which allowed me to disassemble the chip, insert the connector into the computer. Attention! Trial! I warm up the engine. O miracle!
The readings of the electronic tachometer are 590 rpm, which is within the normal range for a unit with a manual gearbox when consumers are turned off (dimensions, headlights, fan, air conditioning, ...). Now, looking at this simple device, you can turn the engine wisely. Have you been eaten? No problem. And here you have two ... exits.
The tachometer in the car informs the driver about the crankshaft speed and helps him choose the right gear. As a result, it is possible to extend the life of the engine and delay the need for its repair as much as possible.
In most cars, analog-type tachometers are installed, which are a device with a dial and an arrow. When the pointer approaches the red zone, the driver shifts the gear one step up. Unfortunately, the required type of device is not installed on all cars, which forces the car owner to act independently. Below we will consider how to install and connect a tachometer with your own hands.
Types of devices
Two types of tachometers are installed in cars - analog and digital. The former have a simple design, and the main elements are the dial and the hand. As for digital devices, they are made in the form of a small screen, which displays the current number of revolutions.
In addition, tachometers are:
- Remote. Such devices, as a rule, are installed by the car owner himself and are mounted on the dashboard of the car. For fixing, a special bracket is provided. Remote digital tachometers are considered the best option for controlling crankshaft speed at idle. Their advantage lies in the smaller error. Digital tachometers are often used to check the standard device. In addition, they look original and give the car originality.
- Regular. These tachometers are provided by the manufacturer and are mounted in the dashboard of the machine. Convenience is that the driver perceives information by the movement of one arrow. He does not need to be distracted by the evaluation of several indicators at once. Most often, it is a pointer tachometer that is used on cars, and electronic devices, as a rule, are produced in a remote format and are designed for self-installation.
In cars with an injection engine, it will not work to connect a tachometer through the ignition. The best solution is to connect the device to the engine ECU controller. The work is carried out in several stages. To begin with, connect the mass to the car body, and the “positive” conductor to the “plus” of the ignition. The tachometer has two outputs - to the crankshaft position sensor (DPKV) and to the control unit. The device that is connected to the computer captures the pulses directly from the controller of the control unit.
The diagram shows how to connect a tachometer to the computer
How to connect a tachometer on cars with a gasoline engine
Before installing a tachometer on a car with a carburetor, read the instructions (comes with the device). If not, take the following steps:
- Fix the tachometer in the chosen place, which is determined by the type of mechanism.
- Connect the black wire to the car body.
- Put the red wire on the ignition lock terminal, through which 12 volts are supplied when the ignition system is activated.
- The third wire may have a different color. It is worth noting that the ignition system in the car is of two types - non-contact and contact. In the first case, connect the tachometer (its third wire) to the voltage switch, and in the second - to the distributor breaker
The diagram shows how to connect a tachometer to a gasoline engine
How to connect a tachometer in a car with a diesel engine
To begin with, we will deal with the principle of operation of the device on diesel cars. It consists in reading the pulses that are sent by the terminal located in the generator. This process is complex, so all work is best done from a viewing hole. The process consists of the following steps:
- Remove the protective cover from the generator. Be careful not to let dirt get into the mechanism.
- Install the tachometer and connect it to the generator. To do this, on the casing of the power source, find the terminal marked "W", and then connect the output of the device to it.
There are cases when it is not possible to find the mentioned terminal. In this case, to connect the tachometer, you will have to disassemble the generator. Take one wire that connects the rectifier assembly and the winding, then connect it to the tachometer wire. Perform isolation of the junction, and after that, assemble the generator according to the reverse algorithm.
Installing the tachometer takes a minimum of time. But in the absence of minimal knowledge about the design of a diesel engine, the principles of its operation, as well as the features of a tachometer on cars with a diesel engine, it is better to trust professionals.
How to check if the device is working properly
Let's say you managed to connect a tachometer on a car with a diesel or gasoline engine. But for further operation, it is important to know the reasons for the failure of the device. For example, the tachometer needle may start to jump or other problems will come out. In general, the following causes of breakdowns can be distinguished:
- The appearance of vibration when the motor is running for a long time, which can damage the display.
- Oxidation of contacts, detachment of tips or violation of the integrity of the insulation.
The faults discussed above can be identified and eliminated independently. If the sensor fails, it needs to be replaced. In the most difficult cases, when the diagnostics did not give results, it is worth contacting the service station.
Video: Digital Division Digital Tachometer Wiring Diagram
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The standard instrument torpedo VAZ 2105 is not equipped with a tachometer. This unit allows drivers to monitor the speed of the crankshaft of the vehicle's engine. Experienced auto mechanics know how to put a tachometer on a VAZ 2105.
Part Selection Rules
Essential car tool
You can install this unit with your own hands. This will require the following tools and materials:
- screwdrivers,
- wiring diagram,
- keys,
- insulating tape,
- wires.
First you need to find out the principle of operation of the unit in question. The pulses read by this device enter the ignition coil, displaying information on the screen. Auto mechanics recommend buying an electronic tachometer. When choosing this device, one should take into account the structural features of the VAZ 2105. Otherwise, the tachometer will show revolutions with a slight error. You can install a universal unit with switches. To do this, connect it to any type of engine.
In the selection process, one should also take into account the fact that there are pointer and electronic tachometers. You can install a tachometer on a VAZ 2105 of the first type with a tuner. The second type is the Balsat TX-319t model. It is a microprocessor device, the main task of which is to monitor the operation of the "five" engine. If necessary, the driver can choose the most suitable mode. Before you figure out how to install a tachometer on a VAZ 2105, you need to consider the capabilities of the car:
- crankshaft speed measurement for 2-6 and 8-cylinder engines,
- availability of hours
- the ability to remember the maximum and minimum temperatures,
- the presence of a stopwatch,
- the ability to measure the acceleration of the crankshaft.
The installation of an electronic tachometer provides for self-adjustment of the backlight. The advantages of the Balsat TX-319t auto mechanics include the presence of a standby mode. This feature significantly reduces energy costs.
Installing the instrument
How to connect a tachometer of this type is of interest to many car owners of the VAZ 2105. To begin with, the mounting location is selected. Then the "minus" wire is connected to the vehicle body. The plus wire is connected to the appropriate ignition terminal. It has a voltage of 12 watts.
The backlight allows you to see the speed at any time of the day, so auto mechanics recommend installing just such units. Before starting work, you need to figure out how to connect a tachometer of this type. For this, an appropriate scheme is used. The backlight wires are connected to the size switch. If the auto is of the injection type, then the device is connected to the controller of the electronic motor control system. In this case, reading is carried out from the last element. Installing a tachometer from another car is prohibited, as difficulties may arise in the operation of the mounted unit.
Everyone knows that a tachometer is included in almost every dashboard in modern vehicles. However, not all drivers know exactly why this device is needed. In this article we will tell you what, in fact, a tachometer is, what they are, and we will analyze the main causes of its technical malfunctions.
A tachometer is a device that measures and shows in real time the number of revolutions of the crankshaft of the power apparatus. It can monitor changes in engine speed to avoid too low or, conversely, high crankshaft speeds.
In the process of driving a car or other vehicle, the device helps the driver to upshift in a timely manner, based on his testimony. Even the most inexperienced motorist will be able to change speed in time when the arrow of this device approaches the red zone or, conversely, drops down to the minimum. Also, it is worth saying that with the help of a tachometer, the desired mode of operation of the engine is selected.
Tachometers are both digital and analog, they can reset the received data, and the accuracy of their readings is rather arbitrary and can change.
Digital tachometers have an electronic display that displays all the necessary information about the speed of the power unit. Such devices are used to set up and adjust the operation of the economizer, electronic ignition, as well as the entire engine.
The analog tachometer is more popular and used more often than the digital one. And all because of the ease of use. When driving, special accuracy is not required, the speed is shown by an arrow moving along a calibrated dial. If the operation of the sensors is incorrect, then the arrow twitches and it becomes impossible to control the speed. The design of this device has been created and changed over the years, so using it is simple and reliable.
If, when starting the engine and while driving the vehicle, the tachometer needle jumps or points to the zero mark, this means that the device is out of order. There may be several reasons for this. However, most often, the cause of the breakdown is the replacement of high-voltage ignition wires. Poor wiring condition can also cause the tachometer to malfunction.
Malfunction in the operation of the tachometer
If signs of a malfunction appear, for starters, you should pay attention to the general condition of the wiring. Very often, damage to the wires or lack of contact in them can cause a breakdown of the tachometer. Various minor defects, in the form of traces of corrosion, minor cracks or loose fastenings, are easy to eliminate, but if the damage is serious, the wiring will need to be replaced.
An equally relevant cause of failure is the installation of silicone ignition wires instead of regular ones. This is because the per unit resistance of silicone wires is very different from the resistance of the factory wires. As a result, the shape of the current pulse changes. If you reduce the value of the resistor on the KP board, then the malfunction is eliminated by itself.
With regard to digital tachometers, a common cause of device failure is often a breakdown of a special digital screen that shows the current parameters of the car. To resume the operation of the device, you will have to change the LED display.
It is also not necessary to exclude the breakdown of other parts; it is necessary to identify which element is broken and replace it with a new one.
Why does the tachometer needle jump
To find out why the tachometer needle is twitching, it is necessary to perform the following manipulations:
1. On the dashboard, find the “Check” lamp and check if it lights up. If not, then, most likely, the system diagnostics will not be able to determine the malfunction.
2. Perform a wiring test by testing the voltage level on the plus and minus wires, and check the condition of the connections.
3. If other equipment or instruments do not work correctly, it is imperative to check the mass, because this detail is often overlooked.
4. Check the condition of the contacts of the distributor and the capacitor on its cover, as it could be broken during operation.
5. Also, you need to check the circuits in the ignition system.
6. If you have recently repaired the device or replaced it, then it just needs to be configured. To do this, you need to adjust the zero position and the device itself, adjust the connection quality and adjust the toggle switch on the back of the unit.
7. If the arrow jumps when the engine reaches high speeds, then the switch is broken and needs to be replaced.
Buy a tachometer for a car
The digital tachometer looks like a scoreboard with luminous numbers that show the frequency of movement of the motor parts.
It is useful when performing ignition electronics tuning operations, setting the fuel saturation state, when the engine is running at full power, or when gradual acceleration is required. It is considered the most accurate and, most often, is chosen, if necessary, to adjust the idle speed or check other devices similar to it.
As for the analog tachometer, they are presented as a dial with an arrow. Such a device is considered more modern, popular and convenient, since the dial is easier for drivers to perceive and allows you to analyze the situation much faster than in the case of numbers. Therefore, when choosing a tachometer, you need to decide which characteristics are preferable and more important for you. However, one way or another, the presence of this important sensor is very necessary on the road, if only because it will allow you to determine in time about the presence of various problems in the engine of your car.
Installing a new tachometer with your own hands, a phased progress of work
You can install a tachometer on any machine, this procedure is not complicated and does not require contacting a workshop. However, the installation process itself depends on which engine you have under the hood - diesel or gasoline. I propose to consider the methods of connecting the tachometer in more detail.
Installing a tachometer on a car with a gasoline engine
If your car is equipped with an ignition system, then you first need to mount the device itself. Very often, drivers operate a remote tachometer.
Directly the scheme of mounting the device looks like this:
1. The “minus” wiring, which often has black insulation, is connected to the vehicle ground.
2. The power wiring usually looks red and is connected to the appropriate ignition switch terminal.
3. If the car circuit is contact, then the wiring that is connected to the measuring input of the device is connected to the ignition coil terminal connected to the distributor breaker. When a non-contact circuit is used in the machine, the third wire is connected to the switch.
If the tachometer is equipped with a backlight, then it is connected to the dimensions of the machine using a special ignition switch terminal.
Installing a tachometer on a car with a diesel engine
1. When your car has a diesel engine, the test lead of the device must be connected to the generator terminal marked with the symbol "W".
2. If you cannot find it, you need to disassemble the generator and get to the wiring that connects the winding and the rectifier.
4. Ultimately, you need to assemble the generator back.
As you can see for yourself, tachometers are different, so it is very important, before buying such a device, to ask the seller if this unit will work correctly on your car.
Surprisingly, until quite recently there were no tachometers at all and the drivers somehow coped. However, modern motorists are used to the fact that everyone makes special settings for them. Rumor has it that the manufacturers of the Mazda car brand want to bury such a device as a tachometer and exclude it from the instrument panel.
