GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 Envoy - 2WD 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - SIR

Caution: Refer to SIR Special Tool Caution in the Preface section.

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 Diagnostic System Check - SIR. All SIR diagnostics must begin with the Diagnostic System Check - SIR. The Diagnostic System Check - SIR determines the following results:
    2. • Proper AIR BAG warning lamp operation
    • Ability of the SDM to communicate through the data link connector (DLC)
    • Existence of SIR current and/or history diagnostic trouble codes (DTC)
  2. Refer to the diagnostic table as directed by the Diagnostic System Check-SIR. The diagnostic tables will help enable you to diagnose any SIR system malfunction. Bypassing these procedures may result in the following problems:
    3. • Extended diagnostic time
    • Incorrect diagnosis
    • Incorrect parts replacement
  3. 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 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 AIR BAG warning lamp flashes seven times and then turns off when the ignition key is turned ON.

    2.

  2. This step checks to see if the scan tool powers up.

    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 current or history diagnostic trouble codes (DTCs) present.

    5.

  5. This step checks to see if there are communication DTCs (U-codes) present.

    6.

  6. This step checks to see if DTC B1000 (ECU Malfunction) is present.

Diagnostic System Check - SIR

Step

Action

Yes

No

1

  1. Note the AIR BAG warning lamp while turning the ignition switch ON.
  2. The AIR BAG warning lamp should turn OFF after flashing seven times.

Does the AIR BAG warning lamp flash seven times and then turn off?

Go to Step 2

Go to Symptoms - SIR

2

Install a scan tool.

Does the scan tool power up?

Go to Step 3

Go to Scan Tool Does Not Power Up in Data Link Communications

3

Attempt to 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 Class 2 Device in Data Link Communications

4

  1. Use the scan tool to request the SIR diagnostic trouble code (DTC) display.
  2. Record the displayed DTC(s) on the repair order, specifying as current or history.

Does the scan tool display any current or history DTCs?

Go to Step 5

System OK

5

Does the scan tool display any DTC's which begin with a "U"?

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

Go to Step 6

6

Does the scan tool display DTC B1000?

Go to DTC B1000 in Body Control System

Go to Diagnostic Trouble Code (DTC) List