Airbag testing is extremely important when purchasing a used vehicle. The health and often the life of the driver and passengers largely depends on the availability and performance of these devices. Autocode tells you how to check if your car has airbags and how to make sure they are working.
Where are the airbags located?
Almost every modern car has similar devices. Before checking for airbags, you need to know where they are located. Depending on the class and configuration, the vehicle can be equipped with the following types of devices:
- frontal (located in the steering wheel and upper part of the dashboard);
- side (installed in doors or seat backs);
- knee (mounted under the steering wheel and glove compartment);
- curtains to protect the head (located behind the ceiling trim between the car pillars);
- central (attached in the armrests between the chairs).
Expensive vehicle models can be equipped with several or all of the above types of airbags. Budget cars most often have only front-facing devices.
How many airbags are there in modern cars?
In 2021, there are only a few older car models that have no airbags at all. Every year there are fewer and fewer of them.
| Number of pillows | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Driver's front airbag | — | + | + | + | + | + | + | + | + | + | + |
| Front passenger airbag | — | — | + | + | + | + | + | + | + | + | + |
| Side front airbags (2) | — | — | — | — | + | + | + | + | + | + | + |
| Curtains (2) | — | — | — | — | — | — | + | + | + | + | + |
| Driver knee pad | — | — | — | + | — | + | — | + | — | + | + |
| Rear side airbags (2) | — | — | — | — | — | — | — | — | + | + | + |
| Front passenger knee airbag | — | — | — | — | — | — | — | — | — | — | + |
Most modern cars have between 2 and 7 airbags. 8, 9 and 10 pillows can only be found on a few car models.
How to check for airbags
Stage 1. Visual inspection of the vehicle interior
The location of the airbags in the car is easy to recognize by the presence of the inscriptions SRS or Airbag on the plugs to which they are attached. To gain complete confidence in the presence of this element of the security system, remove one of the plugs. The easiest way to check the airbag in the steering wheel is to remove the special pad from the steering wheel.
However, making sure you have an airbag is only half the battle. Unscrupulous sellers have long learned to imitate the presence of this security device. Quite often, instead of deployed airbags, dummies are installed, and the old plugs are simply replaced with new ones. This is done in order to save money, since replacing a tripped device, depending on the car model, can reach several tens of thousands of rubles.
Stage 2. Functionality check
At the second stage, it is important to check whether the airbags deployed previously or not. Therefore, we once again carefully inspect the interior of the vehicle. An indirect sign that the car was in an accident and the airbags deployed could be:
- incomplete matching of the color of the plugs with the general palette of the interior trim;
- the presence of traces of restoration of the upholstery of the seats;
- the presence of dents, severe abrasions, chips or scratches on the plugs;
- traces of windshield replacement.
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You can check the functionality of the airbag by carefully examining its condition. After removing the plug, inspect the protection device. The presence of damage to the airbag shell or the gas generator (squib), which is responsible for its timely operation in the event of a collision, is not in favor of the seller. Most likely, he is trying to deceive you.
Restoring the dashboard after the airbag deployed
Repairing the instrument panel after an accident is one of the most labor-intensive tasks in the SRS passive safety system. To replace the airbag and “sew up” the dashboard, you need to completely remove the dashboard. The most difficult thing to do is restore the appearance of the trim on the passenger side - if the plastic is sealed or sheathed with material carelessly, it will be noticeable.
Restoring the panel after the airbags are deployed is carried out in the following sequence:
- the negative terminal is disconnected from the battery;
- the glove compartment is removed;
- the instrument panel is dismantled;
- the fastenings of the instrument panel frame are unscrewed;
- the panel is dismantled and completely disassembled.
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In this case, it is necessary to disconnect all the wires from the dashboard that interfere with removal, remove buttons, deflectors, etc. from the panel. Complete restoration of the dashboard with the installation of new airbags sometimes costs more than tens of thousands of rubles, so car owners are often offered to only restore the casing, without repairs and installation of airbags. But even such work is not cheap; many car owners try, if possible, to find a used instrument panel at car dismantling yards. As a rule, installing second-hand parts is cheaper than a complete repair, and besides, the original panel looks more natural - if the dashboard is restored, it is still noticeable upon careful examination. The restoration of the instrument panel after an accident is carried out by tuning studios; the work is divided into several stages:
- dismantling the dashboard;
- preliminary cleaning and treatment of the dashboard;
- sealing damaged areas using special adhesives;
- making patterns from material chosen by the customer;
- installation of covers on the restored instrument panel;
- Installation of dashboard, electrical connection.
At the request of the car owner, the instrument panel is decorated with decorative chrome elements or natural wood inserts, and an additional acoustic system is installed. The tuned panel looks very impressive, while all the defects that were previously present on the dashboard are hidden.
How to Test an Airbag Crash Sensor
Another way to conclude that the protection device is working is to observe the behavior of the special warning light on the dashboard. By the nature of its operation, you can check how serviceable the airbag control system is. To do this, turn the ignition key and look at the panel:
- if the pillow light continues to light after the other indicators have gone out, the shock sensor may be faulty;
- if the light does not light up at all, there is a possibility that the owner of the car turned it off on purpose, which means he has something to hide from the buyer.
Unfortunately, home-grown craftsmen have long learned to make changes to the filling of protection systems. Even if the indicator on the dashboard behaves as it should, this does not give one hundred percent confidence in the serviceability of the impact sensor and airbags.
Principle of operation
The security unit was developed in the middle of the last century. With the introduction of electronics, it has undergone some changes, but the principle of operation has remained virtually unchanged. Automakers do not adhere to any standards; moreover, many of them use their own developments.
At first glance, this appears to imply a narrow specification of the constituent parts. In fact, everything is just the opposite. Main components of the block:
- a set of sensors;
- airbags;
- SRS unit;
- wiring;
- lamp on the instrument panel;
- squib;
- belt tensioners.
The general principle has remained unchanged for many years. And this is what he looks like.
- When an impact occurs, sensors are activated - there can be up to 10 or even 15 of them. They transmit information to the SRS unit about the location and force of the impact.
- The electronic unit processes this information. Taking into account the side of the impact and the number of passengers, it sends a signal to activate the airbag and belt.
- The squib fires and the airbag covers are knocked out.
- Bleeding air through a special valve or hole.
In addition to the points listed above, it is necessary to clarify one point. When the airbags deploy, Crash Data is recorded in the electronic unit. After this it stops functioning.
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How to check an airbag with a tester
You can verify that the protection system has not worked previously by measuring the resistance of the squib using a conventional tester. For check:
- turn off the ignition and remove the key from the connector;
- remove the terminals from the battery;
- disassemble the airbag.
After this, we set the tester to ohmmeter mode and check the resistance at the connector of the protection device. Any deviations from the norm should alert you.
By the way, scammers have learned to bypass this diagnostic method by installing resistors with suitable resistance. If you lack the necessary knowledge and skills, testing airbags with a tester can lead to inadvertent activation of the safety device and injury. If you are not confident in your abilities, contact an experienced master.
Bottom line
In order to find out more accurately about the condition of the airbags, you need to contact independent specialists. Using diagnostic equipment and the skills to work with it, they will quickly determine not only the state of the passive protection system, but also the reasons why certain problems occurred, and will also establish the fact of intervention in the electronics in order to turn off the failure indicator.
A passive protection device is an important system in a car that protects the health of the driver and passengers. This is why it is so important that it is in working order.
How to check an airbag with a multimeter
A multimeter or diagnostic scanner is equipment that connects to a special connector on the on-board computer and allows you to check the functionality of almost all devices and mechanisms of the vehicle, including the serviceability of airbags.
The cost of professional-level devices varies between 50-60 thousand rubles. A multimeter from the Middle Kingdom will cost an order of magnitude cheaper. The diagnostic scanner allows you to check the serviceability of the airbag control unit, identify the facts of the activation of the squibs, and also check whether any third-party changes have been made to the program. To work with a multimeter, you will additionally need a computer or laptop with specialized software, and of course, certain knowledge. Therefore, when buying a used car, it is better to check the functionality of the security systems at a reputable service center.
Briefly about the design of pillows and the principle of operation
The first airbags were located in the steering wheel, as well as in the front panel opposite the first row passenger, such airbags are called front airbags. Later, a huge number of different pillows appeared, which began to be located in the backs of the front seats, in the body pillars, etc.
Airbags are a set of systems and elements that work as one. The system called “Airbag” includes: a control system, pillows (elastic, dense nylon fabric), and a gas generator. The latter can be of two types - solid fuel and hybrid.
How it works?
After the sensors detect the impact, the signal from them goes to the control unit. Then the unit gives a command to the gas generators, after which the squib is “shot” and the solid fuel charge, which consists of silicon dioxide, potassium nitrate and sodium azide, is ignited. The resulting gas in the form of a cloud instantly fills the cavity of the pillow, turning them into a soft barrier, against which one or another part of the body hits. By the way, all the above actions occur in a matter of seconds.
Airbags that are fired cannot be repaired, they cannot be folded back like a parachute, so they are completely replaced.
