We all know that airbags are essential in the event of an accident, having the role of providing protection for drivers, but also for passengers against the impact with hard surfaces in the car, at high speeds.
Airbags began to be used in the 1970s and statistics indicate that they have saved many people who were in danger of losing their lives in car accidents, since then. Many times, however, car owners have noticed that the airbag indicator on the dashboard lights up.
Although many choose to disregard this aspect and the importance it can have, this article seeks to inform you about the most common problems that may occur, as well as their significance.
The airbag sensors are triggered in the event of an accident and, for this reason, are called accident sensors.
They are positioned both in the front and on the sides of the car, to ensure protection from both frontal and side impacts. Depending on the make, model and year of manufacture of the car, their number may vary.
How does an airbag sensor work?
The principle of operation of an airbag is quite simple. This is a system that has the role of detecting the speed with which the vehicle decelerates. Deceleration is also called negative acceleration and represents the rate of change of speed in a car when the braking process is initiated.
Depending on the detected speed, the system takes action and transmits this information to the control unit and to all component parts of this system. This sensor determines not only the speed but also the intensity with which the impact happened , particularly important factors in activating or not the airbags.
There are two types of sensors - table and roller type. The ground sensor, located in the front area of the car, has the role of determining how strong the impact was.
Composed of two sensors, located at the engine level and in the area where the passengers are seated, this device is able to correctly assess how dangerous the impact was and when the airbag must be deployed to protect the driver and passengers.
The second sensor is in the form of a helical spring. This helical spring is able, through the voltage generated by an impact, to send a signal to the electrical circuit.
Every time you start the car, a check is made of the airbag sensor circuits, a process signaled by a warning light that flashes on the dashboard. Normally, after the check is completed and if everything works in normal parameters, the light on the board will go out. But if the LED stays on, it is a sign that we have a possible fault.
If the sensor in the airbag is broken, the light on the dashboard stays on and the solution to this problem is to change the sensor.
You need to know that the way the onboard signal lights up can mean a certain problem. It is advisable to check in your car’s manual what are the error codes that may occur and what they actually mean.
To make a correct diagnosis, it would be advisable to use an extremely precise tool, able to scan and read the car’s errors. A professional who owns this tool can help you fix the problem in a very short time, through accurate diagnosis.
If you recently needed to change the battery, the spare battery in the airbag may also have suffered. Even if you change the battery, the warning light on the dashboard continues to flash and can mislead you. It is good after each such operation to eliminate the error that occurs with the help of the diagnostic tool.
Problems with the airbag spring
This spring has the role of maintaining the connection between the airbag and the electrical cables. If the problem occurs at this level, due to wear and tear over time, it is advisable to take the car to a mechanic that has the necessary tools to diagnose such a problem and change the clock. The airbag module is particularly sensitive to water or even mild humidity.
Located in the driver’s and passenger’s seat on the right, this sensor can be exposed to corrosion over time and short-circuited. When this happens, a DTC code appears and the dashboard light stays on.
It would be wrong to assume that you know exactly where each sensor in your car is located. To find out exactly, it is good to read the car’s technical book. The most common locations include the bumper in the front area, in the vicinity of the condenser, inside the engine, in the passenger seat, or even in the front wing of the car.
Resetting an airbag sensor
Resetting a sensor can be done using an OBD2 (on board diagnostic) scanner. To reset the airbag, you need to follow 2 steps - first, you need to disconnect the battery.
So, locate the battery under the hood. As you can see, it is provided with a positive terminal and a negative terminal. From the negative terminal, unscrew the nut and disconnect the cable clip. The second step - reconnecting the battery.
After removing the clip, wait more than 5 seconds, then tie the cable back in place. After following these steps, the sensors have been reset, including the airbag, which means that the light will disappear from the dashboard.
How to change a faulty sensor
It is good to know that changing a sensor is not an extremely easy task. But, in order to be able to do it, you need the technical book of the car to know in detail the process of how to mount each part. First, it is necessary to locate the malfunctioning sensor according to the instructions in the technical book.
Whilst you do this the engine must be stopped. Make sure you have all the necessary tools at hand. Disconnect the battery so that the airbag is not triggered accidentally Wait at least 3 minutes after disconnecting the battery. Use a digital multimeter if you need to check the sensor.
Normally, such a sensor is powered by less than 10mA. Find out this information before you start working. Disconnect the 4P connectors. To change the front airbag sensors, it is necessary to disconnect the respective connectors from the sensors in the side area of the driver and the passenger on the right.
How can you tell if a sensor is faulty
If a sensor does not operate as it should , this will be signaled by the on-board warning light. Although normally, when starting the car, this light will flash, a sign that the integrity and proper functioning of the system is checked, the persistence of this light on the board signals a problem. Depending on how it flashes, the reason behind the fault can be interpreted and found out.
In the case of airbag sensors, it is advisable not to use a digital multimeter for verification, as this can trigger the car’s airbags and create additional problems to the ones you already have , not to mention expensive.
If the airbags do not deploy on a violent impact, it is obvious that they have failed. Also, after such an impact,it would be good to change the entire system.
Seek the advice of specialists to decide which is the most suitable measure for you and your car. Since your life and that of the passengers depend on the airbags and their optimal operation, it is good to let the specialized personnel take care of these operations.
If you still insist on changing the sensor at home, it is good to know certain aspects from the beginning and to be informed from the technical book of your car. The operation involves disconnecting the battery. To consume all the current, it is good to leave the headlights on.
Wait a quarter of an hour to make sure the airbags have run out of power and will not start. Disconnect the sensor in question and replace it. Sometimes it may be necessary to have access to disassemble the front panel and doors. After completing the operation, use the OBD2 scanner to reset the error.
How much does it cost to replace a sensor
Although the part itself is not necessarily expensive, replacement labor requires experience and dexterity. The replacement procedure can take as long as 2 hours, even if it was done by a professional. Therefore, due to the fact that it is a process that takes time, but which also has a high degree of difficulty, it can be quite expensive.
The price also varies depending on the type of car, the design, the steps to follow. Before investing in buying a sensor and changing it at home, make sure you know what the labor entails and you can complete it, to avoid wasting time and money, as well as other installation problems.
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