Diagnostic System Check

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.
^ 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:

1. Remove all water.
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 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 tables as directed by the Diagnostic System Check - SIR. The diagnostic tables will assist you in diagnosing 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 repairs or diagnostic procedures. This will verify that you correctly performed the repair. This will also verify that no other SIR system malfunctions exist.

CIRCUIT DESCRIPTION
The AIR BAG Fuse supplies ignition positive voltage to the inflatable restraint Sensing and Diagnostic Module (SDM) at terminal A1. When the ignition switch is first turned to the RUN position, the SDM responds by performing tests on the SIR system while flashing the AIR BAG warning lamp seven times. The SDM then commands the Instrument Panel Cluster (IPC) to turn the AIR BAG warning lamp OFF through the Class 2 serial data circuit. If the SDM detects a malfunction, the SDM will command the Instrument Panel Cluster (IPC) to turn the AIR BAG warning lamp ON.

DIAGNOSTIC AIDS
Intermittent concerns that are indicated by a customer that can not be duplicated or verified by a Diagnostic Trouble Code (DTC) that is retrieved as a history DTC or a current DTC, are usually caused by circuit and connector concerns. Refer to Testing for Electrical Intermittents and Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Test Step 1 - Step 3:

Test Step 4 - Step 5:

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 and then turns OFF when the ignition key is first turned ON.
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) and the instrument panel cluster (IPC).
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.