Anti-lock braking system is installed in almost every modern car, and it is great for helping drivers to avoid wheel locking. Cars with ABS provide maximum braking performance, resulting in shorter braking distances. To diagnose the operation of the anti-lock braking system, the driver has a special indicator on the instrument panel. When it lights up, the computer systems of the car warn the driver that the ABS is not working at the moment, and the wheels are likely to lock if the brake pedal is pressed firmly. The anti-lock braking system, if the car is equipped with it, must be maintained in working order, moreover, there are not many reasons why the ABS light is on.
How the ABS status indicator should work
The ABS system can be divided into several functional blocks to make it easier to understand the problem due to which the corresponding indicator on the instrument panel comes on. Note that the anti-lock braking system consists of:
- Rotation sensors. Usually there are 4 of them - one on each wheel;
- ABS module;
- Devices for monitoring the correct operation of the ABS module;
- ABS indicator on the dashboard.
If the anti-lock braking system lamp on the instrument panel lights up after starting the engine or while the vehicle is moving, then the ABS system is disabled. Many drivers mistakenly believe that they have problems with the braking system when the ABS light is activated, but this is not at all the case. The corresponding indicator is responsible for diagnosing the brakes on the car.
In the first seconds after starting the engine, all indicators on the instrument panel should light up. If at this moment the ABS light is off, then it is faulty.
Why is the ABS light on
Based on the ABS device, it can be concluded that the system malfunction indicator may be on for the following reasons:
- Problems with sensors installed on wheels;
- Malfunctions in the ABS control unit;
- Defective cables between elements, transmitting information about their condition;
- There are problems with the crown on the hub.
All described malfunctions can manifest themselves directly while driving. For example, vibrations on bumpy roads often cause wire breaks. When driving off-road, dirt can stick to the sensors or sand gets clogged in them, which will not allow them to transmit correct information to the system control unit, and it will note the malfunction with the ABS light on on the dashboard.
The ABS light came on: what to do
The surest way in such a situation is to use diagnostic equipment, which will allow you to determine from which sensor the signal is not transmitted to the control unit and what errors are in the operation of the ABS.
You can continue driving a car with a lit ABS icon, but you need to understand that the anti-lock braking system will not work normally.
In winter, on ice, failure of the ABS can lead to skidding braking, blocking of the wheels and skidding of your Renault. Therefore, it is important to find and correct the reason why the lamp came on.
How the system worksABSfine
Recall that ABS - Anti-lock Braking System- in the car it prevents the wheels from locking and consists of a system of sensors that control 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, the hydraulic unit distributes the pressure to the brake pads.
The main task of the anti-lock braking system- change the pressure in the line of the brake system in such a way that, based on the data on the speed of rotation of the wheels, the car can urgently brake, and at the same time maintain controllability.
Modern ABS systems are reliable and are often paired with EBD, which distributes braking forces. The most vulnerable point in anti-lock braking systems is the wheel sensor, because it is constantly exposed to dirt and shock, for example, when repairing wheel hubs.
You will understand that the ABS system works in your Renault when, with intensive braking on a slippery surface, the brake pedal begins to vibrate (give in the leg, twitching and jerking), and a characteristic crackling sound will be heard.
Why does the error appearABS
Normally, the ABS light comes on immediately after starting the engine and goes out after a couple of seconds when the onboard computer checks (and approves) the operation of the system itself.
If the light comes on while Renault is in motion, or does not go out soon after starting the engine, the reason could be that:
- ABS fuse blown
- the ABS wheel sensor is out of order - 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 cut off, the terminals are oxidized
- the voltage in the on-board network has dropped below 10.5 V (the battery is dead, the generator does not work, etc.)
- the electric motor of the hydraulic pump is out of order
- the hydraulic valve or the ABS control unit are out of order (rare breakdown).
Also, the ABS lamp may light up after an illiterate repair of your Renault due to the inept actions of the master 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 fluctuations. Normal working voltage is 12-14.2V.
If the ABS warning lamp on your Renault lights up, the search for the causes of the malfunction is worth start with fuses.
Then you need to inspect the wheel sensors for integrity, check the wiring. An oxidized sensor connector or a frayed wire is often the cause of the problem.
- If the ABS icon comes on on the Renault dashboard after a recent replacement of brake pads or hubs the master may have forgotten to connect the ABS sensor connector. Or it needs to be cleaned from dirt.
- If the icon comes on after a long period of slipping, it is enough to brake vigorously several times - and the icon will go out. In this case, this is the normal reaction of the anti-lock braking system to Renault skidding.
- If the ABS lamp goes out, then flashes again- the reason must be looked for in the contacts of the sensors.
You can check the leakage of current from the on-board network, armed with a multimeter.
After you find and fix the problem, do not be too lazy to check the operation of the ABS system with a simple test: accelerate to 40 km / h and depress the brake pedal sharply. Does the pedal vibrate and crunch? This means everything is working as it should.
If the icon does not go out even after fixing the problem, contact the computer diagnostics specialists to determine the error code on your Renault - and fix it (or reset).
- Why the speed of the Renault is floating, we wrote
If the ABS light on the instrument panel comes on, this indicates a malfunction in the vehicle's anti-lock braking system. In most cases, this icon lights up simultaneously with the icons of other related systems: ESP, ASR (directional 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 cases of an error in the engine management system. In the ABS system, as a rule, there are no emergency modes of operation. Failure of one of the devices leads to a complete failure of the entire system.
This is especially dangerous when the vehicle is operated on poor road surfaces. It is necessary to carry out computer diagnostics in order to find out why the ABS light comes on - to determine all possible causes of the malfunction, to take measures to eliminate them.
The main causes of a malfunction of the ABS system
In general, a typical vehicle ABS system looks like.
Typically, the ABS electronic control unit and the modulator (variable valve pump) are combined into a single unit. The principle of operation of the system consists in short-term blocking of the pressure supply to the brake pipe of the wheel, if the corresponding sensor has shown the absence of wheel rotation.
Experienced drivers know that on vehicles without ABS, braking on slippery surfaces by briefly pressing the brake pedal must be applied to prevent wheel locking. If the wheels are blocked, the car becomes uncontrollable, which can lead to an accident.
The main reasons for a malfunction of the ABS system are:
- malfunction of the electronic control unit;
- failure of solenoid valves in the modulator;
- malfunction of wheel rotation sensors;
- damage to the wiring to the wheel rotation sensors;
- damage or clogging of the rotation sensor area (in the picture shown - a gear ring);
- failure of the fuses for the power supply of the ABS unit, especially that serving the pump in the modulator;
- loss of communication on the CAN bus.
The ABS unit can receive and transmit information to other systems: engine control unit, indicator panel, body control unit. Traction control and stability control information is also processed by the ABS control unit.
Troubleshooting
The most reliable way to identify a faulty device, node or sensor is computer diagnostics.
Some cars up to the year 2000 allow the system to be diagnosed using blink codes (closing certain contacts on the diagnostic connector, determining an error code by blinking a warning light). In cars of the Chrysler group, 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 on the instrument panel of Toyota Karina E is on:
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 eliminating errors.
What to do in different situations if the ABS light on the dashboard is on
1. The error code indicates a failure (open circuit or short circuit) of the speed sensor of a certain wheel (for example, rear right)
Such malfunctions are most likely in the ABS system. You should not buy a new sensor straight away. In most cases, the malfunction is associated with damage to the wiring connecting the sensors to the ABS control unit. The best way to determine the location of the break is to "dial" (measure 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 onwards the connection diagram of the ABS unit has the form.
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, it is necessary to disconnect the connector of the ABS unit 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 extreme contacts on the connector itself, it is usually printed on it.
The sensor and the 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 (wiring short circuit). 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 front wheel stand or in the rear row of seats for the rear wheel rotation sensors. If the sensor does not ring, it should be replaced.
Video - why the ABS is lit on the instrument panel 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 the absence of a 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 like this.
The pulse frequency depends on the wheel speed, the amplitude (peak-to-peak) depends on the sensor sensitivity. If the teeth on the wheel axle, from which the information is read by the sensor, are clogged, the amplitude is greatly reduced. The ABS unit may not see this information.
In some car models, a special rubber or plastic ring with magnetic segments transmits information about the rotation of the wheel. Very often, when repairing a hub, car mechanics do not even think about what it is for, and they simply do not install it or remove it deliberately, as an unnecessary element.
Sometimes a pebble gets into the gap between the teeth and the sensor, which moves the sensor, reducing its sensitivity. In such situations, it is necessary to clean the gap and adjust it.
3. Failure of the pressure regulator solenoid valves
The malfunction is considered critical, usually requires an aggregate repair (replacement with a serviceable ABS unit or a new one). Repairing the modulator is extremely difficult.
4. Fault in power supply circuits
In such a situation, the ABS unit may not be diagnosed at all, or the pump. 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 control units of the vehicle to automate control, monitoring and display. The malfunction is complex, specialist intervention is required. The CAN bus represents the twisting of conductors.
If somewhere in the circuit there is an open or short 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, it enters emergency mode.
The ABS system refers to the engine braking system; traffic safety depends on its proper operation. You should not save on its repair and maintenance.
When contacting a service station regarding the repair of ABS, ESP, ASR systems, ask if the workshop is certified for this type of repair. Reputable service stations carrying out repairs and maintenance of brake systems should have a stand similar to that when undergoing 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 the work immediately after the elimination (especially simple removal) of errors. Be sure to require bench and sea trials. In many cases, even after a quality repair, the error reappears after a few brakes and turns.
Some motorists flinch nervously when the ABS light comes on. They believe that in this case, something bad happened to the braking system as a whole. Begins shoveling the entire Internet 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 braking system of the car must be in good condition, only the anti-lock braking system will be inoperative, which is not at all so critical. Of course, she helps out in some critical situations, but this is all fixable and we will talk about this in more detail in our article.
Causes of the ABS light coming on
Let's list the main reasons suggesting 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 sensor of the anti-lock braking system is out of order, it should be checked and then replaced;
The crown on the hub has become unusable;
Defective ABS control unit.
After you have completed the inspection, and the cause, at first glance, has been eliminated, check the operation of the anti-lock braking system. It is very simple to do this, it is enough to accelerate the car to 40 km / h and brake sharply. vibrates and the flashing light goes out.
If a visual inspection of the damage in the sensor circuit before the unit did not give any results, then computer diagnostics will be needed to determine the specific error code of the anti-lock braking system. On cars with an installed on-board computer, this task is greatly simplified. It will only be necessary to correctly decipher the displayed code and determine the location of the problem.
How to independently check for malfunctions of the ABS light coming on?
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 stays on, check the anti-lock 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 is still 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 help the light to light up.
Quite often, the appearance of an orange ABS indicator after a good slip can panic motorists. But you shouldn't worry at all in this case. Slowly brake 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 it is worth carefully examining all the contacts, and, most likely, you will find the reason for this indicator behavior and easily eliminate it.
Fixing ABS light coming on
As mentioned earlier, don't panic. Let's figure out what you can do to fix the problem without going to a car service.
1. Open the hood and disconnect the battery.
2. The ABS electronic control unit is easy to find, it is located under the hood, often in the same housing with a hydromodulator - an element that distributes braking forces. You will recognize it by the multiple brake pipes that are connected to the block, as well as the bundle of wires with a connector.
3. Disconnect this connector and carefully diagnose it for damage or moisture. Blow out the connector and dry as needed.
4. Check the fuses, which most likely needed to be done first. But it’s not scary.
5. If there is a car lift available, then look at it. If not, then use a jack and raise the car. Your task is to inspect the wires going to the wheel sensors for damage. These wires often come off the mounts and rub against the wheel.
6.
Wheel sensors are built in such a way that a wire with a connector at the end leaves them. It can reach one meter. Your task is to find these connectors and check the presence of a contact and its quality. Make sure there is no moisture or rust.
7. If everything is normal, but the ABS light continues to burn, then definitely go to the car service. The error of the anti-lock braking system is not always eliminated by a "reboot" by removing the battery terminal.
Everything described here refers to self-determination and troubleshooting. In a specialized car service, a scanner will be connected to your car, which will determine the breakdown.
The ABS system is an important component of safe driving. It is known that the reason for a considerable number of road accidents lies in the fact that drivers incorrectly use the braking system of the car. In particular, this problem arises in the winter, when the road surface is rather slippery. Let's take a closer look at the composition of the ABS system, as well as tips on what to do if the ABS light comes on.
The ABS system is used in order to minimize driving errors during sudden depressions on the brake pedal. The work of the system is that it simply does not allow all wheels to lock at the moment when hard braking occurs. Pulse braking is used, that is, the wheels start to rotate / stop in a specific order. This solution reduces the risk of a car skidding and ensures the smoothest possible speed reduction of the car.
ABS system composition:
- Wheel rotation sensors. All wheels are equipped with separate sensors.
- Hydraulic block.
- A device that monitors the correct operation of the hydraulic unit.
- ABS light on the dashboard (there is a separate article on our website about the car dashboard indicators).
If you see that the ABS light on the dashboard lights up, this is a sign of certain problems with the ABS system. If everything is working properly, the ABS light should come on when the ignition is turned on and go out after a few seconds. This is in order for the driver to understand that the ABS is active. If the ABS light is on and does not turn off, the reasons may be as follows:
- Problem in connecting cables.
- Failure of control units for the ABS system.
- Lost communication with one of the sensors located on the wheels.
- Failure of sensors.
Broken wires can occur while driving. In addition, constant vibrations often lead to the fact that the cable connection areas are weakened. You can solve such problems with your own hands without much difficulty.
If the ABS light is on for a reason related to the sensors on the wheels of the car, the problem may be debris or dirt getting into them. In addition, it often happens that the wheels are being repaired at the service station, the ABS sensors are turned off and forgot to reconnect. Another option is incorrect wheel installation, which also leads to the fact that the ABS light on the panel is on.
If the ABS light comes on due to the fact that the system control units are broken, it is very difficult to establish the cause on your own. Often, the task can be simplified by an on-board computer displaying an error code, but in such cases, you need to clearly understand how it is deciphered and where exactly the problem arose.
If the ABS light is on, off and on again, most likely a loose connection somewhere. In order to solve the problem, you need to examine all contacts. However, if the indicator is on continuously, it can be very difficult to troubleshoot the problem.
You can try to restore normal ABS function by accelerating on a level road and pressing the brake pedal sharply. However, if after performing this procedure, the light does not turn off, and all efforts are in vain, we recommend visiting a specialized service. There, experts will be able to diagnose the vehicle's ABS system and "cure" it. You should not spare money for such services, since your safety, and maybe even life, depends on it.
