How to Diagnose Airbag Problems

There is no doubt the inflatable restraint system is one of the most important safety features available in today’s automobiles. This is why the owner’s manual makes it clear, if an airbag warning light is on steady or flashing, the system should be diagnosed and repaired as quickly as possible.

The first step in finding out what turned on the light is to see what code is set. Unfortunately there is no standardization in the industry when it comes to the ability to read stored inflatable restraint trouble codes or their definition. This article will review several different methods that are commonly used to diagnose airbag problems.

Retrieving Airbag Trouble Codes

Airbag systems have the ability to store trouble codes to aid in diagnosis. These are retrieved either by an enhanced scan tool capable of interfacing with the airbag module or counting the number of flashes from the airbag readiness light. On some automobiles these will automatically flash and continuously cycle through the stored codes when a malfunction is present. On other vehicles the light stays on steady until a diagnostic mode is activated therefore allowing the light to flash.

Airbag Scan Tools

Enhanced or specialized scan tools often read brake control module data in addition to both active and stored diagnostic trouble codes for the inflatable restraint system. Active faults are the type that turn on the airbag warning lamp, whereas stored ones can be intermittent problems that are indexed in the control modules memory, but because they’re not a constant failure are not responsible for illuminating the warning light.

The combination airbag, anti lock brake system scan tools connect to the standard OBDII diagnostic link connector (DLC), used to retrieve check engine light codes. After the scanner is connected and the ignition is turned on it will be able to access both active and stored trouble codes for the airbag system. These are identified with the letter B in front of the number which indicates a body code, where as the check engine light variety would start with the letter P representing a power train fault.

Deciphering Airbag Flash Codes

Inflatable restraint systems that use the readiness light or warning indicator to communicate trouble codes by rhythmic flashing don’t have the ability to store intermittent faults. Therefore, any retrieved will represent hard failures that are currently causing the light to stay on. The most common method of communication via the flashing of the light is the two digit system.

In order to clarify blinking, the first digit is flashed slowly followed by a short pause and then a second digit is flashed quickly. Multiple faults will also be separated by a longer pause. As an example, code 51 is five slow flashes followed by one quick flash and then a long pause before it either moves to the next one or starts over again with 51.

On vehicles that communicate in this manner, some will have to be placed into a diagnostic mode before the light begins to blink. Procedures to accomplish this are explained in vehicle specific owner’s or repair manuals. As an example on Honda vehicles from the model year 2000 through 2009, terminals four and nine in the OBDII connector can be shorted together with a jumper wire, placing the airbag system into the diagnostic flash mode when the key is turned on in the accessory position.

Tips for Diagnosing Airbag Problems

Best practices for diagnosing and repairing airbag problems include writing down all stored codes on a piece of paper before you attempt to clear them. As with check engine lights always begin diagnosis from the lowest number to the highest. Keep in mind that intermittent stored codes are erasable, but active failures responsible for turning on the warning light will clear automatically after corrected.

The ability to retrieve trouble codes depends on the automobiles capability of delivering them. Although many vehicle owners would prefer the flash type of communication this system actually has less capabilities because it is unable to store intermittent faults. Airbag capable scanners have come down in price over the years.

In fact some models are under $300, but the problem is vehicle coverage is spotty with these cheaper units. Therefore, always confirm your vehicle is compatible before purchasing one of these budget enhanced scanners. If your specific automobile is on the applications list, you will enjoy the benefit of being able to read and diagnose intermittent malfunctions.