The airbag light is on: finding the causes and troubleshooting

Issues discussed in the material:

• Why might the airbag light come on?
• What can be done to resolve this problem?
• What do car enthusiasts think about it?

When a component or device in a car does not work, the vehicle becomes unsafe for everyone inside and outside it. The dashboard, which contains many different indicators, allows you to monitor the condition of the main components of the machine. When the car is started, the airbag light on the panel lights up, signaling its serviceability. After diagnostics are carried out, the indicator goes out on its own. However, sometimes everything goes according to a different scenario: the light continues to light, which means there is an error in the system. And the sooner it is fixed, the better.

How does the airbag light come on?

When the airbag (Airbag) is inoperative, a special icon lights up on the instrument panel. This is almost always a picture of a pillow. Although there are other options.

In some car brands, in addition to the “cushion”, there is also the inscription “Airbag”.

It happens that the system indicator is signed as “SRS”. This is an international designation.

In some cases, there is no icon on the panel, there is only a corresponding inscription.

If the passive safety system is functioning normally, the light only comes on when the driver turns the ignition key. The computer then finishes the test and the light immediately turns off.

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When buying a new car, you should carefully study the panel. If the light does not light, this indicates that the LED is turned off.

Although there is a possibility that the airbag indicator has broken, it is rare. The light bulb turning off looks suspicious. The one who sells the car may try to hide the consequences of the accident in this way.

In a situation where the light turns on and off along with other car devices, this should also alert you. Often this feature indicates that the Airbag was deliberately connected in such a way as to mislead the buyer regarding the performance of the power supply.

The indicator light flickers - the main mistakes in this situation

If you find that the security indicator lamp is blinking constantly, although there are no prerequisites for this, then you need to immediately respond to this situation. Of course, you can rely on the Russian “maybe”, but then no one will be able to guarantee your safety in the event of an emergency. There is, of course, a possibility that the icon came on for a minor reason that does not affect the operation of the airbags. However, you still shouldn’t rely on this abstract possibility, because the consequences can be very dire. That is why you need to know the order of possible actions that eliminate the root cause of this problematic situation.

Autumn is often when a person looks for a solution to a problem on the Internet, or from his good friends. In cases with a flashing security light, this is also quite common. And the most interesting thing is that the answer is found very quickly, the very essence of which can stun professional auto repairmen and experts. Most people, for some unknown reason, advise simply turning off these annoying signals and driving calmly, not paying attention to what they consider to be a “glitch” of the system. There is hardly any need to say that this is fundamentally wrong and a mistake can be costly - this is already clear to every sane person.

Why does the airbag light come on?

When the Airbag light stays on continuously, it indicates that some kind of error has been detected. Therefore, if an impact occurs, the airbag will not perform its function. Of course, driving a car with such a system is very dangerous. How to remove the airbag light that is on? First of all, you need to find out exactly what factors had a negative impact on the operation of the node.

The SRS system, which protects passengers in an accident, contains impact sensors, airbags, an electronic device and a gas generator squib. These are the most basic parts of the SRS, the interaction of which directly affects its operation, and therefore determines the degree of vehicle safety. Most often, incorrect interaction of the links becomes the main reason why the airbag light stays on.

In general, there is nothing complicated in the PB system. It only includes a number of sensors and a special module. It is used to convert the signal received from the sensors into a command to open the capsule with pillows. Such a capsule works instantly, but, like any other devices, over the years the system’s sensors stop working as they should. This leads to the fact that the capsule with PB does not open when necessary. The positive aspect here is the constant checking of sensors carried out by SRS. If a fault can be found, a signal about this is sent to the dashboard.

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All SRS parts interact with each other using wiring. When a signal cannot reach some element, the latter becomes inoperable. This is why it is so important that the wiring is not damaged. This also applies to connectors. If their integrity is broken, the chain breaks. The following factors can cause problems with cables and circuit components:

• any impact on devices associated with seat belt tension;
• alarm connection;
• reinstallation of the front panel, steering wheel and seats;
• cases of short circuit or damaged connectors.

To determine why the system is not functioning, a diagnostic scanner is used. With its help you can find the place where the signal is lost.

Is it possible to drive like this?

The car engine and other components responsible for movement are not turned off; technically, operating the car is possible, but dangerous.

A modern body is tested many times to protect people in a variety of situations, but always with the SRS system working. When it is disabled, the car becomes dangerous.

High rigidity of the body frame can backfire and people will be seriously injured. Tests on dummies showed numerous fractures and other injuries even at moderate speeds, sometimes apparently incompatible with life.

Even in the presence of serviceable airbags, non-functioning belt tensioners led to the mannequins missing the working area of ​​the opened airbag with the same consequences. Therefore, the comprehensive functionality of the SRS is important, clearly and in normal mode.

Nothing will interfere with getting to the repair site, but maximum care will be required in choosing the speed and position on the roadway.

How to check the sensor if the airbag light on the dashboard is on

Nowadays, the most frequently reported breakdowns in cars are the passenger presence sensor on the seat and the spiral PB sensor located in the steering wheel. The job of the first one is to establish the weight of the person who occupies the seat. This parameter allows the device to calculate the approximate age of the passenger.

Technology that allows one to determine a person’s age by weight is used in vehicles for a reason. The security system receives a signal and the front airbag is automatically switched off in cases where a child occupies the seat in front. Due to the small stature of children, anterior spinal cord is very dangerous for them. The impact of a deployed airbag can even cause the death of a child.

Unfortunately, the sensor that determines the passenger's weight begins to work worse and worse over time. It stops functioning due to the seat being moved too often. Such manipulations easily damage the device itself or the wires. If we take into account that the airbag control system continuously monitors the status of all sensors, then if one of them malfunctions, the light immediately starts to light. This indicator indicates that the passive safety system is faulty.

In some cars, the owner can disable the front passenger airbag with his own hands. This is also one of the reasons why the airbag light on the instrument panel may be on. An interesting fact is that if the PB was intentionally turned off, but an adult sat in the chair, it is automatically activated.

When the airbag deactivated light comes on but there is an adult in the seat in front, one of the SRS devices is faulty. Then you should first make sure that the wires under the front passenger seat are intact. If you find damage to the wiring or establish that the “weight sensor” is completely inoperative, it is worth replacing it with a new one.

Another common SRS problem is a malfunction of the airbag spiral sensor. It is located between the steering wheel and steering column. Due to the fact that the device is connected to the board, different buttons on the steering wheel can work. However, this unit also often wears out, causing the buttons on the steering wheel to stop functioning and the driver’s power steering switch to turn off. To fix everything, you need to replace the part by removing the steering wheel.

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Before you begin repairing the unit, you must first remove the negative terminal of the wire from the battery and let the batteries discharge for 10–15 minutes.

• Every car has shock sensors, the number of which depends on the model. These devices are needed to detect a collision. When such devices do not function, the light on the panel also starts to light, indicating an error.
• To ensure that the airbags do not deploy when the seat belt is not fastened, seat belt buckle sensors are used. However, with any manipulation of the lock and if water gets in there, problems occur in the system. An error signal is displayed accordingly on the instrument panel.

To understand what exactly is faulty, a diagnostic scanner is also used.

Cost of replacement parts

Replacing car parts is always a stressful situation for any car enthusiast. It’s understandable, because the car itself is quite expensive, and an unplanned replacement of parts can significantly hit your wallet. But the realities are such that it is hardly possible to do without this measure, because a comfortable, and most importantly safe, ride will directly depend on it.

In the case of replacing parts when a problem is detected with the Airbag system, the situation is as follows. Replacing a contact group will cost about two to three thousand rubles; replacing a sensor can be much more expensive - from 5 to 15 thousand rubles. This applies to relatively minor breakdowns in the system. If a more serious problem occurs, then you may need to replace the airbag kit, which can cost from 15 to 30 thousand rubles. The security system control unit can also fail, and the only way out is to replace it with a new one - from 10 to 50 thousand rubles. This unit can be repaired, which will cost about ten thousand rubles, but no one can guarantee that it will last long. Typically, after repair, the service life of the control unit is approximately three months.

Separately, I would like to say about where exactly to purchase the necessary parts. The optimal solution would be to purchase from official dealers of your car, who can provide a product certificate and a receipt, or through specialized online stores that contact directly with spare parts suppliers.

The desire to save money on cheaper analogues of original spare parts may come back to haunt you in the future use of the car, or a conflict with original parts may be revealed even at the repair stage.

What are the indirect reasons why the airbag light is constantly on?

At the same time, even if all parts of the passive safety system function as expected, the light may still come on. This is explained by the fact that the SRS system includes many electronic devices and cables. Therefore, the error may not appear due to problems with the pillows.

The following factors can influence this:

• The battery is old , so the voltage is not enough for the system to work fully.
• The memory of the electronics control unit was damaged as a result of some kind of accident. A collision or impact will one way or another affect the vehicle's systems. Therefore, after an accident, it is better to reset the memory. And sometimes, in order for the airbag indicator to stop lighting, you cannot do without flashing it.
• The squib wears out , just like other basic components of the car. This happens when the vehicle has been actively used for more than a decade.
• Programs crash . Its main causes are chip tuning or incorrect software update.

Troubleshooting

When srs is on, a strictly verified sequence of actions is needed:

1. At first, the system works on its own - it checks its functionality when the ignition is turned on, and if an error is detected, it records its code;
2. then the mechanic comes in - he reads the code and determines the cause of the breakdown;
3. the system is checked with specialized diagnostic equipment;
4. repair operations are carried out;
5. The control unit memory is updated.

All operations must be performed only with the battery completely disconnected!

What to do if the airbag light is on

As noted earlier, the SRS system checks the condition of all elements every time it is ignited. If diagnostics reveals a problem, the system stores an error code. It is necessary in order to determine the type of malfunction and remove it. To do this, it is not necessary to contact specialists. First, you can try to do everything yourself.

• You need to start with the easiest thing - check the battery and terminal connections, and also remember the date of the last battery replacement. Maybe it's time to buy a new one?
• If the car has just been washed, it is worth preventing moisture from getting into the systems. If this guess is confirmed, there is no need to worry. The water will evaporate and the problem will disappear.
• It is necessary to additionally check the connection of the connectors and the condition of the wiring if the seat belt tension sensor has recently been disconnected or its parts have been changed independently.

If after all these steps and even after replacing the airbag the light is still on, it is better to continue searching for the problem by involving professionals. But problems will be resolved much faster if you first rule out the main possible causes.

In the event of a road traffic accident, certain components of the safety system are usually triggered. If this does not happen, contact with one or more electronic devices is most likely interrupted. So, in the Peugeot 307, for example, the main systems are located in completely different places:

• The security control unit can usually be found in the center console. It only has a digital signature. Therefore, to find out whether this is exactly what you are looking for, you need to enter the block number into the search engine.
• There are four shock sensors in this Peugeot model. The light will remain on even if one of them stops functioning. In this case, the system itself will most likely operate as before.
• Safety pretensioner squibs. They are required to ensure that the belts are firmly secured during an impact.
• Rear, front and side airbags.
• SRS switch.

Driver airbags and seat belt pretensioners are deployed in any frontal collision.

Passenger airbags are only deployed when a person is seated. Its presence is monitored by a special sensor. It is located under the passenger seat.

Once the airbags and pretensioners have already worked, you need to replace the airbag and squibs with new ones. Otherwise, the system will not function, and the car will simply be unsafe.

The airbag, which is located in the steering wheel, is much more difficult to replace.

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Today, one power bank costs at least 4 thousand rubles. For this reason, an airbag emulator is often installed - a 2.2 Ohm resistor. It is placed parallel to the squib connector.

The latter, in fact, is a fuse and is considered the main actuator of the fire safety device. When voltage is applied to it, the coil immediately heats up, igniting the squib itself. During the combustion process, gases are released, which fill the PB. The belt pretensioner squib is mechanical. If a 2.2 ohm resistor is used, it creates the illusion that the filament is operational.

If the passive safety system did not work when you bought the car, and which airbag has already worked, you don’t know; you can’t do without computer diagnostics. Only with its help will it be possible to determine the airbags and belt pretensioners that need to be changed.

When selling a car, some try to completely get rid of accident data, although this is prohibited in many countries. To delete information in the PB system control unit, information about impacts is removed.

There are special programs and technical means for this. They are used by craftsmen, erasing and refilling the memory of the microcircuit from the SRS block.

People in the car will be safe if all components of the vehicle are fully operational. Moreover, when the light is on, this does not mean that the airbag system is inoperative. It is possible to determine whether there are faulty elements in the SRS and correct the situation only after diagnostics.

If any work is planned on the airbag safety system, you must first disable the Airbag. There is an ON/OFF switch for this.

However, it cannot be found in all car models. If there is no switch, you will have to disconnect the battery terminals. This is necessary to ensure that the airbags do not accidentally deploy during the work. Otherwise, replacing them and restoring the interior will cost a decent amount.

Malfunctions

When a malfunction is displayed, the unit stores the corresponding error codes in its memory. There are not many of them, mostly short circuits and breaks in the circuits of sensors, power supply and actuator cartridges. The codes are read using a diagnostic scanner connected to the OBD connector.

The most common components that suffer are those that are subject to mechanical damage or corrosion:

• a cable for supplying signals to the driver's front airbag hidden under the steering wheel, which experiences multiple bends with each turn of the steering wheel;
• connectors under the driver and passenger seats - against corrosion and seat adjustments;
• any components from improperly carried out repair and maintenance operations;
• charge ignition devices that have a long but limited service life;
• sensors and electronic unit - from corrosion and mechanical damage.

Software failures are possible due to drops in supply voltage and blown fuses, as well as after replacing individual components without correctly registering them in the control unit and on the data bus.

Design and operating principle

The design of the AirBag is not that complicated. It consists of a squib with a cushion, a control unit and shock sensors.

Sensors are located around the perimeter of the car and are responsible for the deployment of one or another airbag.

That is, for front AirBags the sensors are located in the front part, and for side ones - in the doors.

For example, in a frontal collision, the sensors receive the force from the impact and transmit a signal to the controlled unit.

In this case, the side force sensors will not receive, and therefore will not transmit a signal.

From the control unit the signal will go to the necessary squibs.

When this signal is received, a chemical reaction will occur inside the squib, which will be accompanied by the release of a large amount of gas, and the pillow, which is a fabric bag with holes, will be filled with it.

These holes are needed so that after filling the pillow quickly deflates.

This is done so that the AirBag is needed only in the first seconds of impact to accept the human body. It is not necessary to keep it in a full state so that it does not impede the ability to get out of the car.

Airbag deployment is one-time only. If it has already been used, you will need to replace the squib and restore the functionality of the system.

SRS system

In all modern cars you can find the SRS marking in the interior. What does it mean? This abbreviation stands for Supplementary Restrain System, which in Russian means “Extended Security System”. Often the phrase Air bag is added to it, which translates as “airbag”. It is the pillows that are the main attribute of the system. But besides them, SRS also includes:

1. Seat belts.
2. Tensioning devices.
3. Shock sensors.
4. Squibs.
5. Electronic control system.

Like any other automotive component, a security system can fail if one small part breaks down or a reliable connection between elements is lost.