GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1997 🢒 Catera 🢒 Restraints 🢒 SIR 🢒 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 (DTC)
  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 AIR BAG warning lamp turns on for 3-4 seconds to verify operation when the SDM recognizes Ignition voltage, applied to terminal 5, is greater than 9.0 volts. The SDM performs Initialization and Continuous Monitoring tests at this time. The SDM sets a current diagnostic trouble code and illuminates the AIR BAG warning lamp when a malfunction is detected. The SDM clears the current diagnostic trouble codes and moves them to a history file when the malfunction is no longer detected and/or the ignition switch is cycled.

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

  1. The AIR BAG warning lamp should comes on after the ignition is first turned to the RUN position.

    2.

  2. The AIR BAG warning lamp should stay on for 3-4 seconds, then switch OFF.

    3.

  3. This test checks for proper operation of the Serial Data line. This test also determines whether history diagnostic trouble codes are stored and, if so, identify them.

    4.

  4. Improper operation of the AIR BAG warning lamp is indicated. This test differentiates a warning lamp stays ON condition from a warning lamp does not come ON condition.

    5.

  5. This test checks for proper operation of the Serial Data line. This test also identifies the stored diagnostic trouble codes and whether they are current or history.

    6.

  6. This test checks for the proper operation of the serial data line. This test also identifies any stored history diagnostic trouble codes.

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.

Did the AIR BAG warning lamp come ON?

--

Go to Step 2

Go to AIR BAG Warning Lamp Does Not Come On

2

Did the AIR BAG warning lamp stay ON for 3-4 seconds, then go OFF?

--

Go to Step 3

Go to AIR BAG Warning Lamp Comes On Steady

3

Note the AIR BAG warning lamp after it goes OFF.

Did the AIR BAG warning lamp come ON again after 1-1.5 seconds?

--

Go to Step 4

Go to Step 7

4
  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the Data Link Connector (DLC). Follow the directions in the scan tool instruction manual.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR Diagnostic Trouble Code display.

Is a current DTC displayed?

--

Go to Step 6

Go to Step 5

5

Does the scan tool indicate no data received?

--

Go to Data Link Connector (DLC) in Wiring Systems

Go to Integrity Check

6
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTC(s) on the repair order specifying as current or history.
  3. When DTC 65 is set, go to DTC 65 Passenger Air Bag Deployment Commanded table.
  4. When DTC 66 is set, go to DTC 66 Driver Air Bag Deployment Commanded table.
  5. When DTC 67 is set, go to DTC 67 Pretensioner Only Deployment Commanded table.
  6. Diagnose the remaining current DTC(s) from lowest to highest.
  7. When only history DTC(s) exist, refer to Diagnostic Aids for that specific DTC. A history DTC indicates the malfunction that the malfunction is repaired (but DTCs were not cleared) or is intermittent.

Was the current DTC diagnosis performed and all current DTC(s) cleared?

--

Go to Step 1

--

7
  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the data link connector. Follow the directions in the scan tool instruction manual.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR Diagnostic Trouble Code display.

Is a (are) history DTC(s) displayed?

--

Go to Step 9

Go to Step 8

8

Does the scan tool indicate no data received?

--

Go to Data Link Connector (DLC) in Wiring Systems

System OK

9
  1. Turn the ignition switch to the OFF position.
  2. Record the displayed DTC(s) on the repair order specifying as history.
  3. Refer to Diagnostic Aids for the indicated DTC. A history DTC indicates the malfunction has been repaired (but DTC(s) were not cleared) or is intermittent.

Was the diagnosis performed and the DTC(s) cleared?

--

Go to Step 1

--