How to check the relay in a car with a multimeter: step-by-step instruction

When the battery on the car or a motorcycle is poorly charged or recharged, so to speak, first of all it is necessary to pay attention to the generator relay. Of course, this problem could be caused by many other reasons, but more often it is in the relay. But how to check the relay with a multimeter? About this and talk.

This element is designed to protect the battery and extend its life for many years. And all this despite its compactness. Therefore, if you suddenly found out that the car gets badly started after the night, noticed any white smudges and a bad job of the starter, then it's time to climb under the hood. Therefore it is important to know how to check the starter relay with a multimeter, because if everything is left as it is, then the battery will "die" pretty quickly.

Definition

Before you check a relay with a multimeter, you need to understand what it is all about - a relay. This device is designed to regulate the current of the car's generator, which prevents it from recharging the battery. Therefore, because of this element, batteries last longer.

By and large, the relay is a voltage regulator that does not allow a voltage greater than 14.5 volts. This device is extremely accurate, and it is mandatory for all types of machines. However, there are several types of relays.

Types

If you strongly generalize, then there are only two species, and they work on the same principle - increase or decrease the voltage to the required value - 14.5 volts. The first view is that the relay is aligned with the brush assembly. It is usually attached to the generator itself, and the relay itself is located in the housing where the brushes are placed.

Also, the relay can be made as a separate device, which is attached to the body of the machine, and the wires from it go to the generator, and then to the battery.

Cases for both types of relays are filled with glue or sealant, and they are not repaired at all. So, if we check the retractor relay with a multimeter and it turns out that it is non-working, then we will have to buy a new one. Fortunately, it is cheap, especially for domestic VAZ cars. Therefore, it is more convenient and easier to buy a new relay, rather than kolupat old.

If it "died", then the battery will be recharged. This means that the relay is time to change. But for this it is important to know how to check the relay with a multimeter, because we need to know that it is in it, and not in any other part of the generator. At least there are two options for checking: without removing it from the car and taking it off.

How to check the relay of the generator with a multimeter, without removing it from the machine?

Signs of failure of the regulator are clearly visible. Especially if the window is below zero. The battery will always be either uncharged or recharged. In the first case, a weak battery charge can be easily determined by the way the starter rotates the motor. He will barely twist it, and to no avail. Sometimes when you rotate the key, nothing happens at all, and the bulbs on the panel go out.

The recharge of the battery is practically the same. It will happen the same thing, plus the electrolyte from the battery cans will boil. Determine the recharge can be reduced in banks of electrolyte. As a result of evaporation, a white coating can also form on top of the battery. Parts of the body under the battery can also have a white coating. Usually, with such symptoms, drivers think that the battery is damaged, but in fact it's all right, but the case in the relay-regulator, and it is on him that must first pay attention. But for this you must know how to check the relay with a multimeter.

It is not difficult to do this. To do this, take our multimeter and set it to the voltmeter mode. With its help, we can measure the voltage at the battery terminals with the motor running. Note that when the engine is off, the normal voltage should be within 12.4-12.7 V. If, for example, the voltage is 12 V, then the battery needs to be charged and to search for the causes of undercharging.

Normal stresses

So, start the engine, install the voltmeter mode on the multimeter 20 V and connect its test leads to the terminals. If the voltage is around 13.2-14 V, it means that everything is in order with the battery. Increase engine speed to 2000-2500. Voltage in this case should grow to approximately 13.6-14.3 V, which is also within normal limits. Now increase the speed to 3500, and the voltage should rise to 14-14.5 V. Approximately in such marks should be the voltage in the working battery with a working relay.

Abnormal values on the multimeter

If the values deviate from the indicated ones to a greater or lesser side, this indicates a fault in the relay. For example, if the voltage drops to 12 V with an increase in engine speed, then obviously something is wrong. Also, an increase in voltage up to 15-16 V indicates a malfunction of the relay-regulator.

Not always voltage surges indicate a relay failure, but very often. Sometimes the generator itself can fail. In any case, when voltage surges occur, it is first necessary to change the regulator, and if the problem persists, then it is necessary to replace the generator and fully test the system.

Check of the combined relay-regulator

If the brush assembly is aligned with the relay, the generator will need to be removed for inspection. To begin with, it is necessary to check the combined circuit of the relay-regulator, which is used today on many foreign cars and even domestic cars.

To do this, we need to remove and disassemble the generator, since the node we need is attached to the generator shaft, along which the brushes walk. We are looking for a "window" for the brush on the generator, unscrew the fastening bolt, we remove the brush assembly and clean it. Usually it is in graphite dust.

Now we need to assemble a special circuit using a power supply with a regulated load. We also need a battery, because the power supply or charger does not work without it. So, connect the charger to the battery and in parallel to the relay-regulator, and to the latter we also connect a 12-volt light bulb.

With this connection, the light will be on - this is normal, since the brush node is the conductor, and in a quiet state the voltage is 12.7 V. Now we need to raise the voltage on the charger to 14.5 V. The lamp should go out when this indicator is reached. After all, 14.5 V is the "cut-off" of tension growth. And if the lamp goes out, it means that the relay has worked, and it is basically a working one.

Otherwise, if the voltage reaches 15-16 V, and the light is on, it means that the relay does not give a cut-off. In this case, it must be replaced with a new one.

Now you know how to check the relay-regulator with a multimeter, and you can do it yourself.