Common Airbag Problems After Deployment
When talking about common airbag problems after deployment, the path of the conversation will rely heavily on the year, make and model of the automobile. This sector of the auto industry has little standardization. Not only do similar parts have different names from different companies, but service procedures vary greatly between manufacturers and models. As an example, the main airbag module on some cars needs to be replaced after an accident. On others, they can be reset. On the latest Chrysler vehicle the inflatable restraint controller resets automatically after the needed parts are replaced. This article provides valuable information about basic system operation and what needs to be performed before the vehicle returns to service.
Airbags on Newer Cars
On newer vehicles, the airbag modules are often separate from the inflation assembly also containing the igniter and nylon bag. Some advanced vehicles are equipped with an ASDM (airbag sensing diagnostic monitor) that is capable of holding enough energy to fully operate for up to 30 minutes, even if the main battery cables have been damaged or disconnected. Other companies have this stored energy in a device called a DERM (diagnostic energy reserve module). Extra caution during service is required when these systems are utilized.
Airbags on Older Automobiles
With first-generation systems on older vehicles, the module is located in the steering wheel for the driver side and in the dash panel for the front passenger side. This one-piece assembly will have to be replaced after the bags deploy, along with some other inflatable restraint components. I-CAR provides a list used by professional damage estimators listing parts needing to be replaced or inspected after an airbag deployment. This list is a PDF document covering 1995 airbag systems on passenger cars.
How the Airbag Inflates
In order for the bag to become inflated within a few milliseconds, it’s necessary to perform a controlled explosion through a device called an igniter assembly. At the center of the igniter is the squib that actually produces a spark. Voltage is applied through the squib which has a pair of electrical pins with an air gap. An arc jumps across the two pins igniting a canister of gas which facilitates its rapid expansion inflating the airbag.
After the Crash Event
If the determination has been reached that the automobile will be repaired, proper service of the airbag system is important. Procedures should be verified by the driver before the vehicle is returned to normal operation. Using a front end collision, with moderate damage as an example, we’ll concentrate on the deployed passenger and driver front airbags. These components are replaceable and should be sourced from reliable suppliers. It’s recommended to use brand-new factory replacement parts when possible.On vehicles built from the model year 2000 and newer, an example of the costs involved would be about $300 per airbag plus labor. On older vehicles, where the module is included as part of the bag assembly, these costs can be as much as doubled. Other parts of the SIR (supplemental inflatable restraint) system will often need replacing as well. The clock spring coil, Crash sensors in the area that sustained damage, along with the control module are a few examples. There are a lot of variables involved in a collision situation as insurance companies paying for the repairs can get involved and try to hold down total costs.
Verifying Proper Operation
After all the repairs are complete, the driver can perform a simple diagnostic test. When the ignition key is turned on, the airbag or SIR light should be illuminated as a self diagnostic test is run. This light should then go out and stay out while driving. If the light doesn’t come on at all with the ignition key on, the system is not ready to deploy. If the light stays on or is flashing, this is an indication that diagnostics are needed. When the light is on steady or flashing the airbag might not deploy in a collision situation.
Event deployment is performed by the igniter contained in the inflation assembly and is responsible for starting a chemical reaction that inflates the airbag. This is typically accomplished through an explosive release of nitrogen gas although other types are used by different manufacturers. Argon and Nitrogen are currently the most common. After repairs are made and the system is restored to its original condition, car owners should review service procedures performed at the shop. Drivers can check proper operation before they hit the road by verifying the airbag light is operating as per design intent.