For 1990-2009 cars

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:

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 to find and repair 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 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.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step checks to see if the scan tool is able to communicate with the inflatable restraint sensing and diagnostic module (SDM).

2. This step checks to see if there are communication DTCs, or U-codes, present.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: SIR Schematics
1 | Install a scan tool. Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications
2 |

1. Turn ON the ignition, with the engine OFF.
2. Attempt to establish communication with the SDM.

Does the scan tool communicate with the SDM?

Go to Step 3

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

3 | Select the SIR display DTCs function on the scan tool. Does the scan tool display any DTCs? | Go to Step 4 | Go to Symptoms - SIR
4 | Does the scan tool display any DTCs which begin with a "U"? | Go to Diagnostic Trouble Code (DTC) List in Data Link Communications | Go to Step 5
5 | Does the scan tool display DTC B1000? | Go to DTC B1000 in Body Control System | Go to Diagnostic Trouble Code (DTC) List