SIR Diagnostic System Check
Diagnostic Chart:
CAUTION: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified in this database and the instructions given in this database 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.
CAUTION: If any water enters the vehicle's interior up to the level of the carpet or higher and soaks the carpet, the Sensing and Diagnostic Module (SDM) and the SDM harness connector may need to be replaced. The SDM could be activated when powered, which could cause deployment of the air bag(s) and result in personal injury. Before attempting these procedures, the SIR system must be disabled. Refer to Disabling SIR System under Air Bags Arming and Disarming. With the ignition OFF, inspect the SDM mounting area, including the carpet. If any significant soaking or evidence of significant soaking is detected, you MUST:
^ Remove all water
^ Repair the water damage
^ Replace the SDM harness connector
^ Replace the SDM
Failure to follow these procedures could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs.
These diagnostic procedures will help you to find and repair SIR system malfunctions. This service category also contains information for repairing SIR system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:
1. Perform the SIR Diagnostic System Check. All SIR diagnostics must begin with the SIR Diagnostic System Check. The SIR Diagnostic System Check determines the following:
^ Proper AIR BAG warning lamp operation
^ Ability of the SDM to communicate through the Data Link Connector (DLC)
^ Existence of SIR Diagnostic Trouble Codes (DTC)
2. Refer to the diagnostic table as directed by the SIR Diagnostic System Check. The diagnostic tables will help enable you to diagnose any SIR system malfunction. Bypassing these procedures may result in the following:
^ Extended Diagnostic Time
^ Incorrect Diagnosis
^ Incorrect Parts Replacement
3. Repeat the SIR Diagnostic System Check after you perform any repair or diagnostic procedures. This will verify that you correctly performed the repair. This will also ensure that no other malfunctions exist.
CIRCUIT DESCRIPTION
The AIR BAG warning lamp turns on for 3-4 seconds to verify operation when the SDM recognizes Ignition voltage, applied to terminal 5, is greater than 9.0 volts. The SDM performs Initialization and Continuous Monitoring tests at this time. The SDM sets a current diagnostic trouble code and illuminates the AIR BAG warning lamp when a malfunction is detected. The SDM clears the current diagnostic trouble codes and moves them to a history file when the malfunction is no longer detected and/or the ignition switch is cycled.
DIAGNOSTIC AIDS
You must diagnose the diagnostic trouble codes in the order specified by the SIR Diagnostic System Check. Failure to do so may result in the following:
^ Extended Diagnostic Time
^ Incorrect Diagnosis
^ Incorrect Pants Replacement
TEST DESCRIPTION
1. The AIR BAG warning lamp should comes on after the ignition is first turned to the RUN position.
2. The AIR BAG warning lamp should stay on for 3-4 seconds, then switch OFF.
3. This test checks for proper operation of the Serial Data line. This test also determines whether history diagnostic trouble codes are stored and, if so, identify them.
4. Improper operation of the AIR BAG warning lamp is indicated. This test differentiates a warning lamp stays ON condition from a warning lamp does not come ON condition.
5. This test checks for proper operation of the Serial Data line. This test also identifies the stored diagnostic trouble codes and whether they are current or history.
7. This test checks for the proper operation of the serial data line. This test also identifies any stored history diagnostic trouble codes.