SRS Diagnostic System Check

CAUTION: In order to avoid deploying the air bag when troubleshooting the Supplemental Restraint System (SRS), use only the equipment specified 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 SRS 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 Supplemental Restraint System must be disabled. Refer to Disabling the SRS. 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 Supplemental Restraint System repairs.

These diagnostic procedures will help you to find and repair SRS system malfunctions. This service category also contains information for repairing SRS system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:

1. Perform a SRS diagnostic system check. All SRS diagnostics must begin with a diagnostic system check - SRS. A diagnostic system check - SRS determines the following:
- Proper AIR BAG warning lamp operation
- Ability of the SDM to communicate through the data link connector (DLC)
- Existence of current and/or history diagnostic trouble codes (DTC)

2. Refer to the diagnostic table as directed by a diagnostic system check -SRS. The diagnostic tables will help enable you to diagnose any SRS system malfunction. Bypassing these procedures may result in the following:
- Extended Diagnostic Time
- Incorrect Diagnosis
- Incorrect Parts Replacement

3. Repeat a diagnostic system check - SRS 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 of the SDM connector C1 through the SDM Fuse. When the ignition switch is turned ON, the SDM responds by performing tests on the SRS 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.

Steps 1 - 2:

Steps 3 - 6:

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 Wiring Systems.

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.
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.