Caution: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified in this manual and the instructions given in this manual. 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 the SIR System.
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 perform the following tasks:- Remove all water.
- Repair the water damage.
- Replace the SDM harness connector.
- Replace the SDM.
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:
- 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 information:
- 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 conditions:
- 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.
| • | 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) |
| • | Extended Diagnostic Time |
| • | Incorrect Diagnosis |
| • | Incorrect Parts Replacement |
Circuit Description
The ignition switch supplies Ignition 1 voltage to the inflatable restraint Sensing and Diagnostic Module (SDM) at terminal 10 using Fuse 21. When the ignition switch is first turned to the RUN position, the SDM responds by flashing the AIR BAG warning lamp 7 times, then turning the lamp OFF, while performing tests on the SIR system.
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 conditions:
| • | Extended Diagnostic Time |
| • | Incorrect Diagnosis |
| • | Incorrect Parts Replacement |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The AIR BAG warning lamp should flash seven times after the ignition switch is first turned to the RUN position.
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The AIR BAG warning lamp indicates improper operation. This test differentiates a warning lamp stays ON condition from a warning lamp does not come ON condition.
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The AIR BAG warning lamp should turn OFF after flashing seven times.
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This test checks for the proper operation of the Serial Data line.
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This test will identify the stored diagnostic trouble codes and whether they are current or history.
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This test checks for the proper operation of the Serial Data line. This test also identifies any stored history diagnostic trouble codes.
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This test refers to the appropriate DTC Table Diagnostic Aids for diagnosis of the history DTCs.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Note the AIR BAG warning lamp while turning the ignition switch to the RUN position. Does the AIR BAG warning lamp flash seven times? | -- | |||||||||
Does the AIR BAG warning lamp come ON steady? | -- | |||||||||
Note the AIR BAG warning lamp after it flashed seven times. Does the AIR BAG warning lamp go OFF? | -- | |||||||||
Is a current DTC displayed? | -- | |||||||||
5 | Does the scan tool indicate no data received? | -- | Go to Data Link Communications System Check in Wiring Systems | Go to Integrity Check | ||||||
Has current DTC diagnosis been performed and the current DTCs cleared? | -- | -- | ||||||||
Is a history DTC displayed? | -- | |||||||||
8 | Does the scan tool indicate no data received? | -- | Go to Data Link Communications System Check in Wiring Systems | System OK | ||||||
Has the diagnosis been performed and the DTCs cleared? | -- | -- |
