Relay and its use in car alarms. Connection diagram for DRL (DRL) via a contact relay in a car How to connect a 5-pin relay

Many improvements to the electrical equipment of a car include the use of power relays. This article discusses the operating principle and several examples of relays used in cars. This article will be useful to all fans of tuning modifications regarding the electrical equipment of the car.

Here are the main characteristics of domestic relays:

• Rated voltage: 12V
• Control current: no more than 0.2A
• Operation voltage: no less than 8.0V
• Release voltage: 1.5 - 5.0V
• Maximum switching current: 30A
• Control winding resistance: 80±10 Ohm

Versions of domestic relays:

• 90.3747-10 - plastic housing without mounting ear
• 90.3747 - plastic housing with fastening eye
• 113.3747 - metal case with fastening eye
• 113.3747-10 - metal body without mounting ear
• 111.3747 - metal case with fastening eye
• 111.3747-10 - metal case without mounting ear.

Relays must be used in cases where switching is required high currents load (20-40A), and this is more than the control output produces (the winding of the relay control circuit usually consumes no more than 0.2A)

Relays with 4 and 5 contacts are available.

Power relays have winding contacts that control the operation of the power contacts (contacts 85 and 86), and the power contacts themselves (30, 87 and 87a).

The operating principle of a power relay is as follows. Voltage is applied to the relay control contacts (winding), the winding attracts the relay power contacts to each other, the relay operates and closes (or opens) electrical circuit with its power contacts. If there is no voltage at the contacts of the control winding of the relay, contact number 30 is permanently closed to contact number 87a. If voltage is applied to the control winding of the relay, then contact number 30 is disconnected from contact number 87a and connected to contact number 87. One of the contacts, 87a or 87, may be missing. In this case, the relay works either only to close or to open the power circuit.

Some imported relays between the 85th and 86th contacts have quenching diodes or resistors, and sometimes both. These elements protect control circuits from overloads during operation of the relay contacts.

If the diode symbol is marked on the relay body, this means that when connecting such a relay, the polarity of the control contacts must be observed.

It is necessary to pay attention to the markings and arrangement of contacts on the relay, as some manufacturers produce relays with non-standard arrangement of contacts.

It should be noted that during prolonged operation of the relay in maximum load modes, the spark that jumps when switching contacts creates carbon deposits between these contacts, which is why the controlled device may not work or work incorrectly. In the place of poor contact, when current flows, excess heat is generated, the current in the power circuits increases, which entails heating of the place of bad contact in the connected circuit, and subsequently the melting of the plastic parts of the places where these contacts are attached occurs. The attachment points of the relay contacts melt, which leads to their displacement relative to their standard position, and due to the appearance of gaps between the contacts, sparking begins, and as a result of these processes, the contact area heats up even more.

Imported relays are considered more reliable; domestic relays are less sealed and wear-resistant.

When choosing a relay, you need to pay attention to the coating of the relay contacts and the connector where the relay is inserted. The most preferred are relays with tinned contacts.

DRL (daytime running lights) – additional lighting devices installed on a car for use during daylight hours. I would like to emphasize that DRLs are intended to indicate your vehicle in front of other participants traffic, and not for additional illumination of the roadway. There is no doubt about the benefits of using DRLs; your car will become noticeable at a distance of several kilometers. This is achieved by using bright LEDs in the DRLs. In this article, I will tell you about the legal aspects of installing DRLs, as well as the various DRL wiring diagrams.

Legislation

Before practicing installing DRLs, I would like to dwell a little on the legal standards for installing DRLs, as well as the rules of their operation.

The very first and basic rule is that unauthorized installation of additional light signals on a car is prohibited. Yes, you are right, you do not have the right to install DRLs on your car if it was not equipped with them by the manufacturer. This will be considered as making changes to the design of the vehicle. For every change in the design of a vehicle, a certificate must be obtained, which in itself is neither quick nor cheap. Otherwise, traffic police officers will issue you a fine, or even take your car to the impound lot.

How so? My neighbor installed DRLs on the Oka and drives calmly! – you ask. He is simply lucky to have loyal traffic police officers who do not pay attention to his DRL - I will answer you.

Once again, unauthorized installation of additional light signals on a car is prohibited if it was not equipped with them by the manufacturer. Therefore, you make any changes to the design of the vehicle at your own peril and risk. It’s a completely different matter if your car’s equipment does not include DRLs, but more expensive trim levels of your model do have DRLs. In this case, you have the right to install DRL without any approval from the certifying authorities.

The first rule for installing DRLs concerns their location on the car body (see figure). If we briefly describe this figure, we get the following:

• DRLs should be installed at a height of 250 to 1500 mm;
• The distance between adjacent edges of the DRLs must be at least 600 mm;
• The distance from the outer side surface of the vehicle to the nearby edge of the DRL should be no more than 400 mm.

Now let’s briefly go through the rules of operation and use of DRLs:

• DRLs should only be used during daylight hours;
• It is prohibited to use DRLs in conjunction with side lights, low beam and high beam headlights, as well as with fog lights.

Everything that is not prohibited is permitted. It's that simple. Separately, I would like to dwell on an important point, it concerns the use of DRLs in conjunction with high beam headlights. The rule sounds something like this: When the high beam signal is briefly signaled, with the headlights turned off side lights and low beam headlights, DRLs should not be turned off. Let me break it down: you are driving with your headlights and side lights turned off, your DRLs are on, when you signal with your high beams to an oncoming car that you are approaching a traffic police post, your DRLs should not turn off.

Just? I also think that there is nothing complicated here. Knowing the legislation and rules for using DRLs, we are ready to move on to the practice of connecting them. Let's start with the simple and incorrect and end with the complex and correct. Let's go!

DRL connection diagram without relay

This is the most simple circuit DRL connections, but also the most incorrect one. I'll describe it a little. With this connection scheme, you supply voltage to the DRLs from the main power circuit of the car. The main power circuit is activated when the key is turned in the ignition switch. Obviously, your DRLs will always work as long as the key is turned in the ignition, no matter what lighting you use. You have no way to turn off the DRLs until you remove the key from the ignition.

As you already know, the use of DRLs in conjunction with other lighting devices is prohibited. I do not recommend connecting DRLs using this scheme.

Connection diagram for DRL from oil pressure sensor

In this part we will tell you how to connect the DRLs so that they turn on when the engine starts. To connect according to this scheme, you will need a 4-pin relay. The principle of operation of the circuit is approximately the same. In the normal state, relay contacts 30 and 87 are open, i.e. no current passes between them, DRLs are turned off.

As soon as you start the engine, dashboard goes out warning lamp oil pressure, the relay contact 86 receives a signal from the oil pressure sensor, this signal excites the coil in the relay, which controls the closure of contacts 30 and 87. After the closure of contacts 30 and 87, your DRLs turn on. This scheme is also not correct because your DRLs will always work as long as your car's engine is running.

DRL connection diagram via 4-pin relay

To connect the DRL according to this scheme, you, as in the previous case, will need a 4-pin relay. Moreover, the connection diagram is absolutely identical to the previous case, only instead of the control signal from the oil pressure sensor, we will use a button in the car interior. Your DRLs will only turn on when you press a button in the cabin.

You can add a little automation to this scheme. In order for the DRLs to go off when the engine is stopped, you can send a signal to the button from the fuel pump, or from the same oil pressure sensor. This scheme already has the right to life, because you can control the DRL operation depending on your driving conditions.

The only downside is that you need to manually turn off the DRLs (press a button in the cabin) when you turn on the low beam headlights, and also manually turn on the DRLs when driving during daylight hours.

Connection diagram for DRL via 5-pin relay

This scheme is the most correct and automated; I recommend connecting the DRLs according to this scheme. This circuit uses a 5-pin relay. Let's talk a little about the operating principle of a 5-pin relay. The 5-pin relay has 2 power outputs. In the normal state, the first of the power terminals is closed, the second is open. After applying a control signal to the relay, the first output will become open and the second will become closed. This seems complicated, but let's look at an example and everything will become clear.

In the picture:

• Contacts 85 and 86 are control contacts. Depending on whether there is voltage on them or not, contacts 87 or 87A close;
• Contact 30 – power supply contact of the relay. It is to this that voltage must be supplied to power consumers;
• Contacts 87 and 87A – contacts for connecting consumers.

Let me give you an example. There is no voltage on contacts 85 and 86; power through the relay goes to the consumer at contact 87A. There is voltage on pins 85 and 86, the relay switches power to the consumer on pin 87.

How to connect:

• We supply power to the DRLs and headlights through pin 30. For greater automation, take power from the main circuit of the car, which turns on when the ignition is turned on;
• We connect DRLs to contact 87A, which will always be on;
• We connect the headlights to pin 87, which will turn on only when the DRLs are turned off;
• To contacts 85 or 86 (it doesn’t matter), we apply a control signal from the headlight button in the cabin;
• We connect the remaining contact 85 or 86 to the car body.

With this connection, either the DRLs or the headlights may work. When the car is turned off, both the DRLs and headlights are turned off.

In my opinion, this is the ideal option.

Below you will find information from one manufacturer; there are other manufacturers and foreign analogues. For this part of the article, the main thing is to make it clear to the average car enthusiast that relays can be interchangeable, have different schemes, different quantities contacts depending on the purpose.

Domestic relays of this series mark the normally closed contact as 88. In imported relays this contact is everywhere called 87a

Typical schemes relay. Tsokolevka.

Scheme 1

Scheme 1a

According to scheme 1, the following 5-contact (switching) relays are produced:

With 12V control - 90.3747, 75.3777, 75.3777-01, 75.3777-02, 75.3777-40, 75.3777-41, 75.3777-42

With 24Volt control - 901.3747, 901.3747-11, 905.3747, 751.3777, 751.3777-01, 751.3777-02, 751.3777-40, 751.3777-41, 751.3777-42

According to scheme 1a with an anti-interference resistor:

With 12V control - 902.3747, 906.3747, 752.101, 752.3777, 752.3777-01, 752.3777-02, 752.3777-40, 752.3777-41, 752.3777-42

With 24Volt control - 903.3747, 903.3747-01, 907.3747, 753.3777, 753.3777-01, 753.3777-02, 753.3777-40, 753.3777-41, 753.3777-42

Scheme 2

Scheme 2a

According to scheme 2, the following 4-pin (closing/closing) relays are produced:
With 12V control - 90.3747-10, 75.3777-10, 75.3777-11, 75.3777-12, 75.3777-50, 75.3777-51, 75.3777-52, 754.3777, 754.3777-01, 754.37 77-02, 754.3777-10, 754.3777-11, 754.3777-12, 754.3777-20, 754.3777-21, 754.3777-22, 754.3777-30, 754.3777-31, 754.3777-32

With 24V control - 904.3747-10, 90.3747-11, 901.3747-11, 905.3747-10, 751.3777-10, 751.3777-11, 751.3777-12, 751.3777-50, 1, 751.3777-52, 755.3777, 755.3777-01, 755.3777-02, 755.3777-10, 755.3777-11, 755.3777-12, 755.3777-20, 755.3777-21, 755.3777-22, 755.3777-30, 755.3777-31, 755.3 777-32

According to scheme 2a with an anti-interference resistor:
With 12V control - 902.3747-10, 906.3747-10
With 24Volt control - 902.3747-11, 903.3747-11, 907.3747-10

Scheme 3

Scheme 3a

According to scheme 3, the following 4-contact (breaking/switching) relays are produced:
With 12V control - 90-3747-20, 904-3747-20, 90-3747-21, 75.3777-20, 75.3777-202, 75.3777-21, 75.3777-22, 75.3777-60, 75.3777-602, 75 .3777-61, 75.3777-62

With 24Volt control - 901-3747-21, 905-3747-20, 751.3777-20, 751.3777-202, 751.3777-21, 751.3777-22, 751.3777-60, 751.3777-602, 751.377 7-61, 751.3777-62

According to scheme 3a with an anti-interference resistor:
With 12V control - 902-3747-20, 906-3747-20, 902-3747-21, 752.3777-20, 752.3777-21, 752.3777-22, 751.3777-60, 751.3777-61, 62,

With 24Volt control - 903-3747-21, 907-3747-20, 753.3777-20, 753.3777-21, 753.3777-22, 753.3777-60, 753.3777-61, 753.3777-62,

ATTENTION!!!
Relays of the 19.3777 series have a housing similar to the one above. The circuit of these relays has protective and decoupling diodes. Such relays have a polarized winding. These relays are not mentioned here in the article because they have limited use.

Relays of modern cars.

Differences and variety of relay numbers mean different mountings, housing design, degree of protection, coil control voltage, switched currents and other parameters. Sometimes when choosing an analogue it is necessary to take into account some parameters.

According to scheme 5, the following 4-contact (closing/closing) relays are produced:
With 12V control - 98.3747-10, 982.3747-10
With 24V control - 981.3747-10, 983.3747-10

According to scheme 5a with an anti-interference resistor:
With 12V control - 98.3747-11, 98.3747-111, 982.3747-11
With 24V control - 981.3747-11, 983.3747-11

How to turn a “minus” into a “plus” and vice versa? How to hook up to an electric drive? How to open the trunk with the alarm key fob? How to block the engine from starting? There is an answer to all these questions: using a relay.

Knowing how a relay works, you can implement various schemes connections to the vehicle's electrical wiring.

Usually relay has 5 contacts (there are also 4-pin and 7-pin, etc.). If you look at relay carefully, you will see that all contacts are signed. Each contact has its own designation. 30, 85, 86, 87 and 87A. The figure shows where and what contact is.

Pins 85 and 86 are the coil. Contact 30 is a common contact, contact 87A is a normally closed contact, contact 87 is a normally open contact.

At rest, i.e., when there is no power to the coil, contact 30 is closed with contact 87A. When power is simultaneously supplied to contacts 85 and 86 (one contact is “plus” and the other is “minus”, no matter where it goes), the coil is “excited”, that is, it is triggered. Then contact 30 is disconnected from contact 87A and connected to contact 87. That’s the whole principle of operation. It seems to be nothing complicated.

A relay often comes to the rescue during installation additional equipment. Let's look at the simplest examples of using relays.

Engine lock

The blocked circuit can be anything, as long as the car does not start if the circuit is broken (starter, ignition, fuel pump, injector power, etc.).

We connect one coil power contact (let it be 85) to the alarm wire, on which a “minus” appears when arming. We apply +12 Volts to the other contact of the coil (let it be 86) when the ignition is turned on. Contacts 30 and 87A are connected to the break in the blocked circuit. Now, if you try to start the car while the security is on, contact 30 will open with contact 87A and will not allow the engine to start.

This scheme is used if you have a “minus” from the alarm to blocking when arming. If you have a “minus” from the alarm to blocking when disarming, then instead of contact 87A we use contact 87, i.e. the circuit break will now be on pins 87 and 30. With this connection relay will always be in working condition (open) when the engine is running.

We invert the polarity of the signal (from “minus” we make “plus” and vice versa) and connect to low-current transistor alarm outputs

Let’s say we need to get a “minus” signal, but we only have a “positive” signal (for example, a car has positive limit switches, but the alarm system does not have a positive limit switch input, but only a negative input). The relay comes to the rescue again.

We apply our “plus” (from the limit switches of the car) to one of the coil contacts (86). We apply “minus” to the other contact of the coil (85) and to contact 87. As a result, at the output (pin 30) we get the “minus” we need.

If, on the contrary, we need to get a “plus” from a “minus”, then we slightly change the connection. We apply the initial “minus” to contact 86, and apply “plus” to contacts 85 and 87. As a result, at the output (pin 30) we get the “plus” we need.

If we need to make a good powerful “ minus" or "plus", then we also use this scheme.

We supply the alarm output to pin 85. We apply “plus” to pin 86. We apply a signal of the polarity that we need to receive at the output to pin 87. As a result, on pin 30 we have the same polarity as on pin 87.

Opening the trunk using the car alarm key fob

If the car is electric drive trunk, then you can connect to it with a car alarm to open it from the alarm key fob. If the alarm outputs a low-current signal to open the trunk (and most often this is the case), then we use this circuit.

First of all, we find the wire to the trunk drive, where +12 Volt appears when the trunk is opened. Let's cut this wire. We hook up the end of the cut wire that goes to the drive to pin 30. We hook up the other end of the wire to pin 87A. We connect the output from the alarm to contact 86. We connect contacts 87 and 85 to +12 Volts.

Now, when a signal is sent from the alarm to open the trunk, the relay will work and “plus” will go to the trunk electric drive wire. The drive will operate and the trunk will open.

These are just a few wiring diagrams using relays. You can find a few more schemes using relays on the website in the category

In this article I will give some examples relay used in cars, their differences and
some use cases.
Domestic relays and their characteristics:
1. Power supply range: 8…16V.
2. Rated voltage: 12V.
3. Control current: no more than 0.2A.
4. Operation voltage: not less than 8.0V.
5. Release voltage: 1.5…5.0V.
6. Maximum current in the power circuit: 30A.
7. Winding resistance: 80±10 ohms

90.3747-10 in plastic case without mounting flange;
90.3747 - in a plastic case with a mounting flange;
113.3747 - in a metal case with a mounting flange;
113.3747-10-in a metal case without mounting flange;
111.3747 - in a metal case with a mounting flange;
111.3747-10-in a metal case without mounting flange.

Power relays, imported and domestic, perform the same function.
Their main difference is in quality and switched contacts. There are relays with four and five contacts, but all relays have coil contacts, these are 85 and 86 contacts.

In some imported relays, quenching resistors or diodes are installed between these contacts, and sometimes both. These elements are used to protect control circuits from overloads that occur when the relay coil circuit opens.

The following picture shows the original relay used in Audi car with built-in quenching resistor.

If a diode icon is shown on the relay body, it means that when turning it on, it is necessary to observe the polarity on the control contacts. Often these diodes are installed in a connector (the mating part is a block or soket) into which the relay is inserted.

Relay diagram containing a diode and connecting its winding:

When voltage is applied to the control contacts, the relay is activated and closes or opens the electrical circuit with power contacts. Power contacts are always marked as 30, 87 and 87a. The 30th contact is always present in the relay. Without supplying voltage to the winding contacts, it is permanently closed to contact 87a. If a signal is applied to the winding, then contact 30 is disconnected from 87a and connected to 87. 87a or 87 contact may be absent, then the relay will only work to turn on or off (close or open) the power circuit.

It is necessary to carefully monitor the markings of the contacts on the relay, because Some manufacturers produce relays with non-standard contact arrangements. The figure shows a BOSCH relay with a different contact arrangement. Contacts 30 and 86 are swapped.

Relays are used in cases where the actuator consumes more current (up to 30-40 amperes) than the control output is capable of producing (the consumption of relay coils usually does not exceed 200 milliamps). Examples of using relays for switching various devices are given at the end of the article.

It is important to note that if the relay has been operated for a long time when switching power circuits in extreme modes, then the spark that jumps when closing or opening the contacts creates carbon deposits between the contacts and because of this, the actuator may not work or will not work correctly. Poor contact generates heat. At the same time, the current consumption in the power circuits may increase (if the contact is poor, the current of the electric motor or light bulb becomes a pulse-start), which leads to heating of the places of poor contact in the switched circuits and, as a result, melting of the plastic parts for fastening the contacts. When fastening parts melt, the contacts shift and a sparking process is added, which further heats the contact point. The figure shows carbon deposits appearing on the contacts of a domestic relay. The switching contact is bent for clarity. White dots - breakdown of carbon deposits by a spark when connecting a consumer; through these places the response contact can be welded, leaving the consumer connected.

Imported relays under the Saturn and San Hold brands have proven themselves to be the most reliable and commercially available; relays from other manufacturers are also used.

On the contrary, domestic relays are unsatisfactory in such parameters as tightness and wear resistance.

It is also important to cover the output contacts and the mating part (connector or socket). The most successful coating for relay contacts is tinning. Examples of oxidizing relay contacts.

Options for circuit solutions for connecting relays.

Signal inversion and load control circuits.

Signal inversion circuits can be used to invert door or trunk switch signals when connecting to an alarm system or in other cases.

These circuits can also be used to amplify the signal when connecting a load controlled by an additional signaling channel. When connecting the trunk lock solenoid, auxiliary hood lock control, auxiliary fog lights, auxiliary sound signals or when connecting other electrical equipment, it is necessary to install a protective fuse in the power circuit (+) 12 Volt (lower diagram).

Connection diagram central lock with an additionally installed activator (activators) to alarms that do not have built-in relays (interface) of the central locking system.

Self-locking engine blocking circuit (self-locking).

To control the blocking relay, you can use a secret button, a reed switch-magnet pair, or a standard control element that issues a control signal of positive polarity when the ignition is on (for example, a power signal on a window lifter or heating rear window). When controlling a button or reed switch, diode D2 is not needed. When controlling a standard unit for unlocking, a button or reed switch is not needed; diode D2 is required.