On-Board Diagnostics

Whenever the ignition key is turned to the "run" or "start" position, the airbag control module (ACM) performs a warning indicator check by turning the AIRBAG warning indicator on. The indicator stays lit for 6 to 8 seconds, then goes off. If the indicator remains off, it means the ACM has checked the system and found it to be free of discernable malfunctions.

The ACM monitors critical input and output circuits within the airbag system, making sure they are operating correctly. Some circuits are tested continuously, others are checked only under certain circumstances. The ACM provides diagnostic information about the airbag system to the technician through the DRBIII via the PCI bus.


Use the diagnostic tests to find the cause of any customer complaint regarding the AIRBAG warning indicator such as:
* Airbag warning indicator does not come on at all
* Airbag warning indicator stays on


Diagnostic Trouble Codes
Airbag diagnostic trouble codes consist of active and stored codes. If more than one exists, diagnostic priority should be given to the active code(s).

Each diagnostic trouble code is diagnosed by following a specific testing procedure. The diagnostic test procedures contain step-by-step instructions for determining the cause of the trouble codes. It is not necessary to perform all of the tests in this book to diagnose an individual code.

Always begin by reading the diagnostic trouble codes using the DRBIII. If more than one code exists, diagnostic priority should be given to the active codes(s).

Active diagnostic trouble codes for the airbag system are not permanent and will change the moment the reason for the code is corrected. In certain test procedures, diagnostic trouble codes are used as a diagnostic tool.

Active Codes
An active trouble code indicates an on-going malfunction. This means that the defect is currently there every time the airbag control module checks that circuit/function. It is impossible to erase an active code; active codes automatically erase themselves when the reason for the code has been corrected.

With the exception of the warning indicator trouble codes or malfunctions, when a malfunction is detected, the AIRBAG indicator remains lit for a minimum of 12 seconds or as long as the malfunction is present.

Stored Codes
Airbag codes are automatically stored in the ACM's memory as soon as the malfunction is detected. With the exception of the Loss of Ignition Run Only code, which is an active code only.

A "stored" code indicates there was an active code present at some time. However, the code currently may not be present as an active code, although another active code could be.

When a trouble code occurs, the AIRBAG warning indicator illuminates for 12 seconds minimum (even if the problem existed for less than 12 seconds). Stored codes display the time in minutes that the code was active, and the number of times the ignition has been cycled since the active code was last detected.

The minimum time shown for any code will be one minute, even if the code was actually present for less than one minute. Thus, the time shown for a code that was present for two minutes 13 seconds, for example, would be three minutes.

Maintain a safe distance from all Airbags while performing the following inspection. If a malfunction is not active while performing a diagnostic test procedure, the active code diagnostic test will not locate the source of the problem. In this case, the stored code can indicate an area to inspect.

If no obvious problems are found, erase stored codes, and with the ignition "on", wiggle the wire harness and connectors, rotate the steering wheel from stop to stop. Recheck for codes periodically as you work through the system. This procedure may uncover a malfunction that is difficult to locate.