GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 Yukon Denali 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - SIR

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 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 assist you in diagnosing any SIR system malfunction. Bypassing these procedures may result in the following problems:
    2. • 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 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal 10. 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 AIR BAG warning lamp OFF. If the SDM detects a malfunction, the SDM will command the AIR BAG warning lamp ON.

Diagnostic Aids

Intermittent concerns that are indicated by a customer that cannot 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 in Wiring Systems and Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

Refer to step numbers on the diagnostic table.

  1. The inflatable restraint IP module switch must be in the ON position to perform the Diagnostic Starting Point.

    2.

  2. The AIR BAG warning lamp should flash 7 times after the ignition switch is first turned to the RUN position.

    3.

  3. The AIR BAG warning lamp indicates improper operation. This test differentiates a warning lamp stays ON condition from a warning lamp does not come ON condition.

    4.

  4. The AIR BAG warning lamp should turn OFF after flashing 7 times.

    5.

  5. This test inspects for the proper operation of the serial data line.

    6.

  6. This test will identify the stored diagnostic trouble codes (DTCs) and whether they are current or history.

    7.

  7. This test inspects for the proper operation of the serial data line.

    8.

  8. This test refers to the appropriate DTC Table Diagnostic Aids for diagnosis of the history DTCs.

SIR Diagnostic System Check

Step

Action

Value(s)

Yes

No

1

Does this vehicle have an inflatable restraint IP module switch?

--

Go to Step 2

Go to Step 3

2

  1. Turn the ignition switch to the ON position.
  2. Turn the inflatable restraint IP module switch to the OFF position and then back to the ON position.

Is the inflatable restraint IP module switch in the ON position?

--

Go to Step 3

--

3

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

Does the AIR BAG warning lamp flash 7 times?

--

Go to Step 5

Go to Step 4

4

Does the AIR BAG warning lamp come ON steady?

--

Go to AIR BAG Warning Lamp Comes On Steady

Go to AIR BAG Warning Lamp Does Not Come On

5

Note the AIR BAG warning lamp after the warning lamp flashed 7 times.

Does the AIR BAG warning lamp turn OFF?

--

Go to Step 9

Go to Step 6

6

  1. Turn the ignition switch to the OFF position.
  2. Connect the Scan Tool to the data link connector.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR diagnostic trouble code (DTC) display.

Is a current DTC displayed?

--

Go to Step 8

Go to Step 7

7

Does the Scan Tool indicate no data received?

--

Go to Scan Tool Does Not Communicate with UART Data Line

Go to Sensing and Diagnostic Module Integrity Check

8

  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order, specifying as current or history.
    3. • When DTC B1051 is set, refer to DTC B1051 Frontal Air Bag and Preten Deployment .
    • When DTC B1018 is set, refer to DTC B1018 Passenger Deployment Loop Short to GND .
    • When DTC B1024 is set, refer to DTC B1024 Driver Deployment Loop Short to Ground .
  3. Diagnose the remaining DTCs from lowest to highest.
  4. When only history DTCs exist, refer to Diagnostic Aids for that specific DTC. A history DTC indicates the malfunction has been repaired or is intermittent.

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

--

Go to Step 3

--

9
  1. Turn the ignition switch to the OFF position.
  2. Connect the Scan Tool to the data link connector.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR diagnostic trouble code (DTC) display.

Is a history DTC displayed?

--

Go to Step 11

Go to Step 10

10

Does the Scan Tool indicate no data received?

--

Go to Scan Tool Does Not Communicate with UART Data Line

System OK

11

  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTCs on the repair order specifying as history.
  3. When DTC B1071 is set, refer to DTC B1071 Internal SDM Failure .
  4. For all other DTCs, Refer to Diagnostic Aids for that specific DTC. A history DTC indicates the malfunction has been repaired or is intermittent.

Has the diagnosis been performed and the DTCs cleared?

--

Go to Step 3

--