Some motorists shudder nervously when the ABS light comes on. They believe that in this case something bad happened to the brake system as a whole. The entire Internet begins to be scoured in search of explanations for the current unpleasant situation. Why did the ABS light come on and what should be done in this case? But panic is inappropriate in this case and hardly justified. The car's braking system must be in good condition; only the anti-lock braking system will be inoperative, which is not at all so critical. Of course, it helps out in some critical situations, but this is all fixable and we will talk about it in more detail in our article.

Reasons for the ABS light to come on

We list the main reasons for a constantly burning ABS light on the dashboard:

- the contact in the plug-in connector has disappeared;

Lost connection with one of the sensors, possibly due to a broken wire;

The anti-lock braking system sensor has failed; it should be checked and then replaced;

The crown on the hub has become unusable;

Faulty ABS control unit.

After you have completed the inspection and the cause has, at first glance, been eliminated, check the operation of the anti-lock braking system. This is very easy to do, just accelerate the car to 40 km/h and brake sharply. will vibrate and the flashing light will go out.

If a visual inspection of damage in the sensor circuit to the block does not produce any results, then computer diagnostics will be needed to determine the specific error code for the anti-lock brake system.

On cars with an installed on-board computer, this task is greatly simplified. You will only need to correctly decipher the displayed code and determine the location of the problem.

We note the fact that the anti-lock braking system functions normally only if the ABS light comes on when the ignition is turned on and goes out after seconds.

First of all, if the ABS light remains on, check the anti-lock brake system fuse and inspect the wheel sensors. It often happens that the sensor connector on the hub is oxidized or the wires are frayed, and if the icon remains on after replacing the hub or pads, then the first logical thought that comes to mind is that the sensor connector is not connected. If the sensor is covered with dirt, this can also cause the light bulb to light up. Quite often, the appearance of an orange ABS indicator after a good slip can cause panic among motorists. But there is no need to worry at all in this case. Brake sharply a few times and everything will return to normal. This is a completely normal reaction of the control unit to this state of affairs.

If the ABS light flashes periodically, then you should carefully examine all the contacts, and, most likely, you will find the reason for this behavior of the indicator and easily eliminate it.

Fixing the ABS light coming on

1. As mentioned earlier, there is no need to panic. Let's figure out what can be done to fix the problem without going to a car service center.

2. Open the hood and disconnect the battery. The ABS electronic control unit is not difficult to find, it is located under the hood, often in the same housing with a hydraulic modulator - an element that distributes braking forces.

3. You will recognize it by the multiple brake pipes that are connected to the block, as well as a bundle of wires with a connector.

4. Disconnect this connector and carefully inspect it for damage or moisture. If necessary, blow out the connector and dry it.

5. Check the fuses, which most likely should have been done first. But it's not scary.

6. If you have a car lift available, then look at it. If not, then use a jack and lift the car. Your task is to inspect the wires leading to the wheel sensors for damage. These wires often fly off the mounts and rub against the wheel. Wheel sensors are built in such a way that a wire comes out of them with a connector at the end. It can reach one meter. Your task is to find these connectors and check the presence of contact and its quality.

7. If everything is normal, but the ABS light continues to light, then definitely go to a car service center. An error in the anti-lock brake system is not always resolved by a “reboot” by removing the battery terminal.

Everything described here refers to troubleshooting and troubleshooting on your own. A specialized car service center will connect a scanner to your car, which will determine the breakdown.

A modern car is equipped with various vehicle status indicators. Most systems are controlled electronically, but the feedback by which the computer communicates with the driver is the blinking of lights or some kind of light elements.

Young drivers may be alarmed by the situation in which the ABS light is on. In this case, there is no reason for critical panic, because the main braking system should remain normal.

The anti-lock braking system helps to minimize driver and road inconvenience when pressing the brake pedal. The wheels do not lock, causing the vehicle to spin or lose control. The car brakes and continues to move in a straight line.

ABS helps with braking impulses by rotating/locking the wheels in a specific sequence. When the system operates, skidding is practically eliminated, and the vehicle speed gradually decreases.

The ABS system includes the following elements:

• hydraulic block;
• electronic sensors located on each wheel;
• an element that monitors the correct operation of the hydraulic unit;
• indicator light on the dashboard.

Identifying problems

If the ABS light comes on while driving, this is a signal that the entire system or its individual elements are not working correctly. A normal sign of performance is that it lights up when the car starts, and after a few seconds it should go out.

At this time, the ABS performance is tested. Signals are sent to all sensors, and response impulses are received from them.

When the ABS icon comes on and does not go out even while driving, this may be a consequence of the following problems:

• connection problem with any sensor on one of the wheels;
• breaking in the control unit;
• poor contact in connecting cables;
• failure in all sensors.

Wire breaks occur while driving, as well as during intense vibrations on a bad road. The connections in the connectors become loose and breakage occurs. These faults can be resolved independently without contacting the specialists of the car company.

Also, the reason why the ABS sensor is on may be that debris or dirt has gotten onto the working surfaces of the sensor located on the wheel. It is enough to wash the car thoroughly and the indicator will go out.

You need to remember how long ago you visited a car service center, because inexperienced technicians diagnose wheels by removing the wires from the sensors. After this, would-be specialists forget to return everything to its original position, and the light on the panel continues to burn.

Malfunctions with the control unit will be more problematic. You can identify them using the on-board computer, which will display a system error code. Using this data, the problem with anti-blocking is calculated. It is unlikely that you will be able to resolve the issue yourself, so a trip to a car service center will be required.

Solving the problem yourself

For those who are used to acting decisively, we can advise you to open the hood and find the electronic control unit. After disconnecting the battery, inspect the case for damage or water getting inside. If necessary, you can dry everything from excess moisture.

We check all connections in the fuse box. It is necessary to know that several fuses can be used simultaneously for ABS operation.

It is worth checking the wires going to the wheel from the ECU. They may become separated or fray during use. Such diagnostics are carried out with the car jacked up.

In some cases, it is enough to accelerate on a flat, empty road and brake sharply. In this case, all systems must work correctly, and the indicator must go out if there is a temporary failure in the ECU.

In cases where the ABS is working normally, but the lamp is still on, it is enough to remove the battery terminal for a few minutes to reset the system. Everything must return to normal.

When none of the suggested cases of putting the display in order helped, you need to boldly go to a car service center in order to identify and eliminate the error using computer accurate diagnostics.

If the ABS light on the instrument panel lights up, this indicates a malfunction in the vehicle's anti-lock brake system. In most cases, this icon lights up simultaneously with the icons of other related systems: ESP, ASR (exchange stability, traction control, etc.)

The ABS error indication shows the complete inoperability of the system, and not the error of its individual elements, as in the case of an error in the engine management system. The ABS system, as a rule, does not have emergency operating modes. A malfunction of one of the devices leads to a complete failure of the entire system.

This is especially dangerous when operating a vehicle on poor road surfaces. It is necessary to carry out computer diagnostics in order to find out why the ABS light comes on - to identify all possible causes of the malfunction, and take measures to eliminate them.

The main causes of ABS system malfunction

In general, a typical car ABS system looks like this:

Typically, the ABS electronic control unit and the modulator (pump with variable valves) are combined into a single unit. The principle of operation of the system is to briefly block the supply of pressure to the wheel brake pipe if the corresponding sensor shows that the wheel does not rotate.

Experienced drivers know that on cars without an ABS system, it is necessary to brake on slippery roads by briefly pressing the brake pedal to prevent the wheel from locking. If the wheels lock, the car becomes uncontrollable, which can lead to an accident.

The main causes of ABS system malfunction are:

• malfunction of the electronic control unit;
• failure of solenoid valves in the modulator;
• malfunction of wheel rotation sensors;
• damage to the electrical wiring to the wheel rotation sensors;
• damage or clogging of the rotation sensor area (in the figure shown - a ring gear);
• failure of the fuses supplying the ABS unit, especially those serving the pump in the modulator;
• loss of communication via the CAN bus.

The ABS unit can receive and transmit information to other systems: engine control unit, display panel, body control unit. Information from the traction control and stability control systems is also processed by the ABS control unit.

Troubleshooting

The most reliable way to determine a faulty device, component or sensor is computer diagnostics.

Some cars produced before 2000 allow diagnosing the system using blink codes (closing certain contacts on the diagnostic connector, determining the error code by blinking the warning light). In Chrysler Group vehicles, error codes can be determined after turning the ignition on and off three times. They will be displayed on the digital odometer.

Video - what to do if the ABS light comes on on the dashboard of the Toyota Karina E:

After reading the error code, it is necessary to decrypt it, if this is not done automatically by the diagnostic scanner software. Next you need to start troubleshooting.

What to do in various situations if the ABS light is on on the instrument panel

1. The error code indicates a failure (open circuit or short circuit) of the speed sensor of a specific wheel (for example, rear right)

Such malfunctions are most likely to occur in the ABS system. You should not immediately buy a new sensor. In most cases, the malfunction is associated with damage to the wiring connecting the sensors to the ABS control unit. The best option for determining the location of the break is a “continuity test” (measuring the resistance in the circuit), starting from the connector of the ABS control unit. To do this, you need to know the electrical diagram for a specific unit.

For Mercedes Sprinter 2005 The ABS unit connection diagram looks like this.

It shows that the wheel sensors are connected to pins 12-13, 16-15, 14-29 and 31-30. In order to ring the sensors from the connector, you need to disconnect the ABS unit connector and find the corresponding contacts. Connector pinout for Mercedes Sprinter (2005 onwards)

If there is no pinout of the connector, you can find the numbers of the outer contacts on the connector itself; it is usually marked on it.

The sensor and wiring are considered to be working if the multimeter readings are less than 1000 Ohms in at least one direction, but not less than 10 Ohms (short circuit of the wiring). If the resistance value is infinite in both directions, there is an open in the circuit or sensor.

It is necessary to check the resistance at the sensor connector. They are located either near the rack for the front wheels, or in the area of ​​the rear row of seats for the rear wheel rotation sensors. If the sensor does not ring, it should be changed.

Video - why the ABS lights up on the dashboard of Priora, Kalina, Grant (fault diagnosis):

If the sensor rings, but the wiring as a whole is not, you should look for a break in the wiring connecting the sensor to the ABS control unit. Sometimes there are up to 3 cases of breakage, especially if the car has been operated for a long time with a faulty ABS system.

2. The error code indicates that there is no signal from a specific wheel rotation sensor.

Certified service stations have special devices that record the shape of electrical signals - oscilloscopes. The electrical signals from the speed sensor should look something like this.

The frequency of the pulses depends on the speed of rotation of the wheel, the amplitude (span) depends on the sensitivity of the sensor. If the teeth on the wheel axle, from which the sensor reads information, are clogged, the amplitude is greatly reduced. The ABS unit may not see this information.

In some car models, information about wheel rotation is transmitted by a special rubber or plastic ring with magnetic segments. Very often, when repairing a hub, car mechanics do not even think about why it is needed, and simply do not install it or deliberately remove it as an extra element.

Sometimes a pebble gets into the gap between the teeth and the sensor, which moves the sensor away, reducing its sensitivity. In such situations, it is necessary to clean the gap and adjust it.

3. Failure of pressure regulator solenoid valves

The malfunction is considered critical and usually requires a unit repair (replacement with a working ABS unit or a new one). Repairing a modulator is extremely difficult.

4. Malfunction in power supply circuits

In such a situation, the ABS unit or pump may not be diagnosed at all. It is necessary to check all fuses responsible for servicing the ABS system.

5. Lack of communication via CAN bus

This is a kind of local network that connects all vehicle control units to automate control, monitoring and display. The malfunction is classified as complex and requires specialist intervention. The CAN bus represents a twisting of conductors.

If there is a break or short circuit somewhere in the circuit, the control units, including the ABS, lose communication with each other, information about the vehicle speed from the engine control unit may not be transmitted to the ABS, and it enters emergency mode.

The ABS system refers to the engine braking system; traffic safety depends on its proper operation. You should not skimp on its repair and maintenance.

When contacting a service station to repair ABS, ESP, ASR systems, ask whether the workshop is certified for this type of repair. Reputable service stations that carry out repairs and maintenance of brake systems must have a stand similar to that used for technical inspection. Simple services of an auto electrician to eliminate errors may not be enough for the correct operation of the ABS.

Do not pay for work immediately after eliminating (especially simply deleting) errors. Be sure to request bench and sea trials. In many cases, even after a high-quality repair, the error appears again after several braking and turns.

Most modern cars are equipped with an anti-lock braking system from the factory, and drivers are already quite accustomed to the constant assistance of ABS when braking. Despite minor shortcomings, ABS turned out to be one of the most effective systems, allowing not only to shorten the braking distance, but also to maneuver during emergency braking.

Any car without ABS, when trying to brake on a slippery road and at the same time make a turn/change lane, is guaranteed to go into a skid, which can end very badly. Therefore, it is enough to drive a car with ABS quite a bit to get used to this level of comfort, and if it fails, most car owners are completely unprepared for this. It often happens that the ABS light is on on the panel, but the driver does not take any action to correct this situation.

Why does the ABS light come on?

The ABS light, located on the dashboard, serves to promptly inform the driver about a malfunction of this system. So, every time you start the engine, the ABS system undergoes a self-test, during which the indicator is always on. It takes no more than three seconds to identify possible faults, after which the indicator goes out. If this doesn't happen, you can rest assured that carefree braking on any surface can be forgotten.

Since ABS is a rather complex system, in order to understand what the problem is when the ABS light comes on, you need to imagine what it consists of. There are three main elements of the system.

1. The electronic unit is the one that makes decisions and controls the entire system.
2. The hydraulic unit is responsible for the pressure in the brake system, and when the wheels are blocked by pressing the brake pedal, it reduces the pressure in the brake system, allowing the wheel to rotate.
3. Sensors that read the number of wheel revolutions. They are located on each hub and constantly transmit information to the central unit.

If the ABS light is on on the instrument panel, an error code, the alphanumeric designation of which is displayed on the on-board computer display, will help you figure out the cause yourself. You can decipher it by reading the car’s operating instructions or searching for information on the Internet.

Advice! If the ABS icon lights up when you start the engine, it is not recommended to start driving. Despite the fact that the car will not be left without brakes, it will be difficult for the driver to quickly get used to the need to brake in a new way. In addition, the performance of some other driving assistance systems depends on ABS.

The ABS icon is on - possible causes of the malfunction

Despite the sufficient complexity of the system, when the ABS and exclamation mark are on after starting the engine, there may be relatively few reasons for this:

If the ABS ESP lights come on, it is still not recommended to continue or start driving. It is worth understanding that if the malfunction is related to sensors, wiring or the battery, you can easily fix them yourself, but malfunctions of the central or hydraulic unit will require the intervention of professionals with the appropriate equipment. You can try to climb into these complex knots on your own only with the necessary knowledge and experience.

What can you do yourself if the ABS light is on?

The very first thing you should pay attention to when the ABS lights up is the error code that will appear on the on-board computer display. Having deciphered it, it will become clear what exactly caused the malfunction and whether it is possible to try to eliminate it on the spot. If the problem is in the sensors, then before searching for a faulty sensor or the location of damaged wiring, you can try turning off the engine for a couple of minutes and starting it again - in some cases the ABS lamp goes out.

If this does not help, you will have to lift the car on a lift or check each sensor, sequentially jacking up all the wheels. It's not a clean job, but it needs to be done. You should first equip yourself with a multimeter that can operate in ohmmeter mode, since the main method of diagnosing sensors is to measure the resistance of each of them. If testing of the sensors does not reveal a malfunction, you should carefully inspect all the wires that connect them to the central unit. The insulation must be intact, and all connecting terminals must be free of signs of oxidation and dirt.

Consequences of a faulty ABS

In the case when the ABS indicator comes on for an inexperienced driver who has never driven a car without an anti-lock braking system, the consequences may not be pleasant, especially in winter. It will not be easy for the driver to remain without the support of this system, and if, out of habit, he tries to fully depress the brake pedal on a slippery road, and besides, making even a small maneuver, he will easily fly off the road with locked wheels.

If the ABS lamp is not constantly on, but only flashes periodically for a certain time while driving, this will also negatively affect safety. The fact is that if the ABS is periodically deactivated while driving, then at the moment the system starts operating, the electric pump begins to take part of the brake fluid. If you press the brake pedal at this moment, it will simply fall to the floor - it is very easy for an inexperienced driver to get confused in such a situation, especially at high speed. Of course, after a moment the functionality of the braking system is restored, but sometimes these very seconds may not be enough to stop the vehicle in a timely manner. If possible, it is still better to contact a professional to diagnose the entire system - you can see how this is done in the video:

You can continue driving a car with the ABS icon on, but you need to understand that the anti-lock braking system will not work normally.

In winter, when there is ice, failure of ABS can lead to skidding, wheel locking and skidding of your Renault. Therefore, it is important to find and correct the reason why the lamp came on.

How the system worksABSfine

Let us remind you that ABS is Anti-lock Braking System- in a car it prevents wheel locking and consists of a system of sensors that monitor the speed of the car and the rotation of its wheels, as well as a hydraulic unit and a control unit. The control unit processes the signal from the sensor, and the hydraulic unit distributes pressure to the brake pads.

The main task of the anti-lock braking system- change the pressure in the brake system line so that, based on data on the speed of rotation of the wheels, the car can brake urgently and at the same time maintain controllability.

Modern ABS systems are reliable and are often paired with an EBD system that distributes braking forces. The most vulnerable point in the anti-lock braking system is the wheel sensor, because it is constantly exposed to contamination and shock, for example, when repairing wheel hubs.

You will understand that the ABS system is working in your Renault when, during intensive braking on a slippery surface, the brake pedal begins to vibrate (feel into your foot, jerking and jerking), and a characteristic cracking sound is heard.

Why does the error appear?ABS

Normally, the ABS light comes on immediately after the engine starts and goes out after a couple of seconds, when the on-board computer checks (and approves) the operation of the system itself.

If the light comes on while the Renault is in motion, or does not go out shortly after starting the engine, the reason may be that:

• ABS system fuse blown
• The ABS wheel sensor has failed - due to mechanical damage or a change in the gap between the sensor and the gear rotor
• contact with the system sensors is lost - the wiring is broken, the terminals are oxidized
• the voltage in the on-board network has dropped below 10.5 V (the battery is dead, the generator is not working, etc.)
• The hydraulic pump motor has failed
• The hydraulic valve or ABS control unit has failed (rare failure).

Also, the ABS lamp may light up after an illiterate repair of your Renault due to the inept actions of a technician who damaged the sensor or wiring.

What to do if the ABS light comes on

In order to prevent problems in the ABS system, you need to constantly monitor the health of the battery, generator and relay regulator. The anti-lock braking system ECU reacts strongly to voltage changes. Normal operating voltage is 12-14.2 V.

If the ABS warning light comes on on your Renault, it’s worth looking for the cause of the problem. start with fuses.

Then you need to inspect the wheel sensors for integrity and check the wiring. Often the cause of the malfunction is an oxidized sensor connector or a frayed wire.

• If the ABS icon lights up on the Renault dashboard after recently replacing the brake pads or hubs, perhaps the technician forgot to connect the ABS sensor connector. Or it needs cleaning from dirt.
• If the icon lights up after a long period of slipping, it is enough to brake intensively several times and the icon will go out. In this case, this is a normal reaction of the anti-lock braking system to the Renault slipping.
• If the ABS light goes out then comes on again- the reason must be sought in the sensor contacts.

You can check the current leakage from the on-board network using a multimeter.

After you find and fix the problem, take the time to check the operation of the ABS system with a simple test: accelerate to 40 km/h and sharply depress the brake pedal. Does the pedal vibrate and “crunch”? This means everything is working as it should.

If the icon does not go off even after fixing the problem, contact computer diagnostic specialists to determine the error code on your Renault - and fix it (or reset it).

• Why the revs on Renault fluctuate, we wrote