Initial Inspection and Diagnostic Overview

The supplemental inflatable restraints (SIR) Diagnostic System Check must always be the starting point for any SIR system diagnosis. The Diagnostic System Check reveals diagnostic trouble codes (DTCs) through the use of a scan tool. It also checks for proper AIRBAG warning indicator operation.

The two types of DTCs that may be recorded are as follows:
1. Current DTCs represent malfunctions currently being detected. Current DTCs are stored in random access memory (RAM).
2. Historic DTCs represent all malfunctions detected since the last time the historic memory was cleared. Historic DTCs are stored in the electronically erasable programmable read-only memory (EEPROM).