GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Body and Accessories 🢒 Data Link Communications 🢒 SIR 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.

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. 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. 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:
    2. • Proper AIR BAG warning lamp operation
    • Ability of the SDM to communicate through the data link connector (DLC)
    • Existence of SIR diagnostic trouble codes (DTCs)
  2. 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:
    3. • Extended Diagnostic Time
    • Incorrect Diagnosis
    • Incorrect Parts Replacement
  3. 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.

Circuit Description

The ignition switch supplies Ignition 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal A1 using the SDM Fuse. When the ignition switch is first turned to the RUN position, the SDM responds by performing tests on the SIR system and then commanding the AIR BAG warning lamp OFF after it has flashed seven times.

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:

    • Extended Diagnostic Time
    • Incorrect Diagnosis
    • Incorrect Parts Replacement

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 to the RUN position.

    2.

  2. This step checks to see if the SIR warning lamp turns OFF after it has flashed seven times.

    3.

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

    4.

  4. This step checks to see if there are any currrent DTCs present.

    5.

  5. This step checks to see if the scan tool can communicate with the SDM.

    6.

  6. This step checks to see if there are any history DTCs present.

SIR Diagnostic System Check

Step

Action

Value(s)

Yes

No

1

Note the AIR BAG warning lamp while turning the ignition switch to the RUN position.

Does the AIR BAG warning lamp flash seven times?

--

Go to Step 2

Go to AIR BAG Warning Lamp Circuit Malfunction

2

Note the AIR BAG warning lamp after it has flashed seven times.

Does the AIR BAG warning lamp go OFF?

--

Go to Step 6

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Install the scan tool.
  3. Turn the ignition switch to the RUN position.
  4. Establish communication with the inflatable restraint sensing and diagnostic module (SDM).

Does the scan tool communicate with the SDM?

--

Go to Step 4

Go to Scan Tool Does Not Communicate with Sensing and Diagnostic Module

4

Use the scan tool to request the SIR diagnostic trouble code (DTC) display for current DTCs.

Is there a current DTC displayed?

--

Go to Step 5

Go to AIR BAG Warning Lamp Circuit Malfunction

5
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order, specifying as current DTCs.
    3. • When DTC B0051 is set, refer to DTC B0051 Deployment Commanded .
  3. Diagnose the remaining DTCs from lowest to highest. Refer to the Diagnostic Trouble Code (DTC) List/Type .

Has the current DTC diagnosis been performed and the current DTCs cleared?

--

Go to Step 1

--

6

  1. Turn the ignition switch to the OFF position.
  2. Install the scan tool.
  3. Turn the ignition switch to the RUN position.
  4. Establish communication with the SDM.

Does the scan tool communicate with the SDM?

--

Go to Step 7

Go to Scan Tool Does Not Communicate with Sensing and Diagnostic Module

7

Use the scan tool to request the SIR diagnostic trouble code (DTC) display for history DTCs.

Is there a history DTC displayed?

--

Go to Step 8

System OK

8
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order specifying as history DTCs.
  3. When DTC B1000 is set, refer to DTC B1000 ECU Malfunction .
  4. For all other history DTCs, refer to the Diagnostic Aids for that specific DTC. A history DTC indicates that the malfunction has been repaired or is intermittent.

Has the diagnosis been performed and all of the DTCs cleared?

--

Go to Step 1

--