Diagnostic System Check

A Diagnostic System Check-SIR:

CAUTION:
^ Refer to SIR Special Tools Caution in Service Precautions.
^ 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 Supplemental Inflatable Restraint (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:
1. Remove all wafer.
2. Repair the water damage.
3. Replace the SDM harness connector.
4. Replace the SDM.

Failure to follow these tasks 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. Refer to the diagnostic table as directed by the diagnostic system check-SIR. 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
2. Repeat the diagnostic system check - SIR 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 ignition switch supplies Ignition 1 voltage to the inflatable restraint Sensing And Diagnostic Module (SDM) at terminal A1 through the SDM Fuse. When the ignition switch is turned ON, the SDM responds by performing tests on the SIR system while the instrument cluster flashes the AIR BAG warning lamp seven times. Then, the SDM commands the instrument cluster to turn the AIR BAG warning lamp OFF through the Class 2 data circuit. If the SDM detects a malfunction, the SDM commands the instrument cluster to turn the AIR BAG warning lamp ON.

DIAGNOSTIC AIDS
When an intermittent concern is indicated by a customer symptom that cannot be duplicated or by a Diagnostic Trouble Code (DTC) that is retrieved as a history DTC without a corresponding current DTC, an intermittent condition may exist. Intermittent problems are usually caused by circuit or connector concerns. Refer to Testing for Electrical Intermittents and Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
1. This step checks to see if the AIR BAG warning lamp flashes seven times when the ignition key is turned ON. The AIR BAG warning lamp should turn OFF after flashing seven times.
2. This step checks to see if the scan tool powers up.
3. This step checks to see if the scan tool can communicate with the inflatable restraint Sensing and Diagnostic Module (SDM).
4. This step checks to see if there are any current or history Diagnostic Trouble Codes (DTCs) present.
5. This step checks to see if there are communication DTCs (U-codes) present.
6. This step checks to see if DTC B1000 (ECU Malfunction) is present.