Diagnostic Starting Point

CAUTION: IN ORDER TO AVOID DEPLOYING THE AIR BAG WHEN TROUBLESHOOTING THE SIR SYSTEM, USE ONLY THE EQUIPMENT SPECIFIED. FAILURE TO USE THE SPECIFIED EQUIPMENT AS INSTRUCTED COULD CAUSE AIR BAG DEPLOYMENT, PERSONAL INJURY TO YOU OR SOMEONE ELSE, OR UNNECESSARY SIR SYSTEM REPAIRS.

DIAGNOSTIC TROUBLE CODES
The "SIR Diagnostic System Check" must always be the starting point of 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. Current Diagnostic Trouble Codes (DTCs) - 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).

SCAN TOOL DIAGNOSTIC
A Scan tool is used to read current and history diagnostic trouble codes and to clear all diagnostic trouble codes after a repair is completed. The Scan tool must be updated to communicate with the SIR system. To use a Scan tool, connect it to the data link connector and turn the ignition switch On. The Scan tool reads SDM serial data from the Data Link Connector (DLC).

INTERMITTENTS / HISTORY CODES / POOR CONNECTIONS
History codes are those indicating that the SDM has previously detected a fault which has since disappeared. Most intermittents are caused by faulty electrical connections or wiring. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).
^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact.
^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal from SA 9206Z connector test adapter kit to check for proper tension, refer to "Checking Terminal Contact".

NOTE: Connector test adapter kit SA 9206Z must be used whenever a diagnostic procedure requests checking or probing a terminal. This will ensure that no damage to the terminal will occur.

^ Poor terminal-to-wire connection. Checking this requires removing the terminal from the connector. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over the wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc.
^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle.
^ Wiring broken inside the insulation. This condition would cause a resistance to show continuity, but if only one or two strands of wire are intact, resistance would be too high.
To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined in "Wiring Repair".