What Turns on the Airbag Warning Light
One of the big problems with the inflatable restraint systems on automobiles is the lack of standardization. Even the icon for the warning light looks different from year-to-year, and between vehicle manufacturers. This lack of standardization continues when diagnostic codes are set. The same code numbers can stand for different things on different automobiles.
When discussing what turns on the airbag warning light on a specific automobile, there are actually a lot of possible reasons. With that said, some are more common than others. This article will provide insight into the capabilities of the airbag warning light and how the system determines a failure is present with automatic diagnostic tests every time the key is turned on.
The Airbag Warning Light
In the mid-90s, the government decided to mandate the inclusion of supplemental inflatable restraint systems to work in conjunction with the vehicle seat belt to help save lives. The government also mandated if the system developed a problem where it might not deploy in an accident the manufacturer would have to turn on an airbag warning light to notify the driver of this situation.
The manufacturers comply with this by running simple diagnostic tests when the key is turned on. Often this is a resistance check or a reference voltage sent out from the control module to the various sensors, input and output devices in the system. If voltage is sent out and doesn’t reach its destination this would be a sign of a malfunction. To simplify what turns on an airbag light, it’s the module looking for diagnostic readings that fall within a specification. Test results that are within the range turn off the light, and those out of range will set a code and notify the driver.
Airbag Flash Codes
On many SIR (supplemental inflatable restraint) equipped vehicles, If the system fails the diagnostic test when the key is turned on, a code will set and the airbag light will begin to flash. These are often two digit codes with the first digit flashing slower than the second digit. As an example, a code 68 would be six slow flashes followed by eight quicker flashes. After the second digit is done flashing the system will move on to the next stored code. If there is only one stored in memory, it will just repeat this over and over again.
Common Airbag Warning Light Problems
Although there is little standardization between vehicle manufacturers, when it comes to airbag safety systems, there are certain parts due to their location or function that are more likely to fail than others. This is especially true on vehicles that are in service for extended periods of time or have high mileage on them. As an example, one of the only moving parts in an inflatable restraint system is the steering wheel mounted clock spring.
This part assures the power reaches the driver side deployment module regardless of steering position. Another component that fails because of its location would be externally mounted crash sensors. Some of these parts are subjected to extreme environments like road salts or violent swings in temperature. Although these components are designed to stand up under these conditions, sometimes it’s their wiring harness or connections that fail after prolonged exposure.
Professional mechanics often look for common problems affecting many of the same year, make and model cars and trucks. Automobiles are known for developing repair trends and this can be used as an advantage by educated shops. Manufacturers issue technical service bulletins identifying these trends. A well-equipped repair center will have access to the publications and be able to identify manufacturer specific airbag problems.
How to Reset the Airbag Light
Inflatable airbags are constantly monitored type systems. This means if the light is on or flashing a defect is present. After the problem is diagnosed and repaired, simply turning on the key will allow the module to detect the issue has been resolved and the system is ready to deploy in an accident. There are situations where manufacturers require special tools to reset a light, but for the most part, on a wide range of vehicles, clearing the code happens automatically after the repairs are completed.
A specific example of this is the stored energy function in some restraint systems. A diagnostic energy reserve module can become depleted in a dead battery situation. After the main vehicle battery is replaced some cars will detect this and turn off the airbag warning light automatically after the reserve is recharged. Some models require a visit to the dealership to have this function reset.
The lack of standardization in the automobile industry when it comes to inflatable airbags prevents this article from identifying exactly what turned on your airbag warning light. It does however, point out some common problems throughout the industry that owners can lookout for. Always remember that repair trends on certain models are identified by the vehicle manufactured and published so professional mechanics are notified about the issues. Car owners looking for professional diagnosis of these complex systems should make sure their repair center has access to factory technical service bulletins.