SIR Diagnostic System Check

SIR Diagnostic System Check Chart:

WARNING: To avoid deployment when troubleshooting the sir system, do not use electrical test equipment such as a battery powered or a.c. powered voltmeter, ohmmeter, ect., or any other type of electrical equipment other than that specified. Do not use a non-powered probe type tester. instructions must be followed carefully, otherwise personal injury may result.


OVERVIEW
The "SIR Diagnostic System Check" must always be the starting point at any SIR system diagnosis. The "SIR Diagnostic System Check" checks for proper AIR BAG warning lamp operation and checks for SIR diagnostic trouble codes using a scan tool.
1. Active diagnostic trouble codes - Malfunctions that are presently being detected. Current diagnostic fault codes are stored in random access memory (RAM).
2. History Diagnostic Trouble Codes - All malfunctions detected since the last time the history memory was cleared. History diagnostic trouble codes are stored in electrically erasable programmable read only memory (EEPROM).

NOTE: Saturn has a unique fault code feature - a second occurrence of the same fault will cause the lamp to stay on even though the fault may have cleared. The code will be stored in history, and if intermittent the code may be active.




PERFORM THE SIR DIAGNOSTIC SYSTEM CHECK
A. The "SIR Diagnostic System Check" checks for the proper Air Bag warning lamp operation, the ability of the Sensing & Diagnostics Module (SDM) to communicate through the serial data line, and whether any SIR diagnostic trouble codes exist.
B. Refer to the proper diagnostic chart as directed by the "SIR Diagnostic System Check." The "SIR Diagnostic System Check" will lead you to the correct chart to diagnose any SIR faults. Bypassing these procedures may result in extended diagnostic time, incorrect diagnosis and incorrect parts replacement.
C. Repeat the "SIR Diagnostic System Check" after any repair or diagnostic procedures have been performed. Performing the "SIR Diagnostic System Check" after all repair or diagnostic procedures will ensure that the repair has been made correctly and that no other malfunctions exist.

CIRCUIT DESCRIPTION
When the ignition switch is first turned "On," system voltage is applied from the AIR BAG fuse to the SDM at the "IGN 1" terminal "A7." The SDM responds by flashing the AIR BAG warning lamp seven times while performing tests on the SIR system. System voltage is also applied from the "IGN 1" fuse through the cluster at the "IGN 1" terminals "H" and "L" to the SDM at the "WARN 1" input at terminal "A9." The SDM responds by grounding the "WARN 1" output and flashes the AIR BAG warning lamp.

DIAGNOSTIC AIDS
The order in which codes are diagnosed is very important. Failure to diagnose the codes in the order specified may result in extended diagnostic time, incorrect diagnosis, and incorrect parts replacement.

ACTIVE CODES
Active codes indicate faults that were present since the last ignition cycle. Active codes can be viewed on the portable Diagnostic Tool (PDT) in the GENERAL INFORMATION or TROUBLE CODES table.

HISTORY CODES
History codes indicate faults that may not be currently detected, but have been present in past ignition cycles. History codes can be viewed on the Portable Diagnostic Tool (PDT) in the MALFUNCTION HISTORY table. History Code 52 cannot be cleared from MALFUNCTION HISTORY.

INTERMITTENT CODES
If a fault occurs intermittently, the first occurrence will result in a stored history code. If the same fault occurs twice within 125 ignition cycles, the airbag telltale will be commanded on and will remain on until the vehicle is serviced. The second occurrence fault will be stored as an active code.