GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing this test, ignition and deployment loop voltages are measured to ensure that they are within their normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 025 SIR Warning Lamp

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The warning lamp does not properly blink ON and OFF.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Diagnostic Aids

When the ignition switch is turned ON, normally, the warning lamp blinks 7 times during 7 seconds.

If the warning lamp stays ON or blinks a second after the normal blinking, 7 times during 7 seconds, it is regarded as a defect, old or current. Inspect the defect with a scan tool.

Step

Action

Values

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

1

Did you perform a Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect the fuse F12.

Is the fuse F12 open?

 

Go to Step 3

Go to Step 4

3

Replace the fuse F12.

Did you complete the replacement?

 

Go to Step 15

--

4

  1. Turn the ignition ON.
  2. Measure the voltage at the fuse F12.

Does the voltage measure within the specified range?

11-14 V

Go to Step 6

Go to Step 5

5

Repair the open power supply circuit for the fuse F12.

Did you complete the repair?

 

Go to Step 15

--

6

  1. Turn the ignition OFF.
  2. Remove the instrument cluster, or clock.
  3. Inspect the air bag warning lamp bulb.

Is the bulb OK?

 

Go to Step 8

Go to Step 7

7

Replace the warning lamp bulb.

Did you complete the replacement?

 

Go to Step 15

--

8

  1. Turn the ignition ON.
  2. Measure the voltage at terminal B14 of cluster connector.

Is the voltage as specified?

11-14 V

Go to Step 10

Go to Step 9

9

Repair the wire between fuse F4 and terminal B14 if cluster connector.

Did you complete the repair?

--

Go to Step 15

--

10

Verify the connection of terminals B14 and B16 of the cluster connector.

Is the connection OK?

Go to Step 12

Go to Step 11

11

Replace the instrument cluster or clock.

Did you complete the replacement?

 

Go to Step 15

--

12

  1. Turn the ignition switch OFF.
  2. Disconnect the I/P module connector.
  3. Disconnect the steering wheel module coil connector.
  4. Disconnect the SDM connector.
  5. Measure the voltage at terminal 7 of the SDM connector.

Is the voltage as specified?

11-14 V

Go to Step 13

Go to Step 14

13

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

14

Repair the wire between terminal 7 of the SDM and the cluster.

Did you complete the repair?

--

Go to Step 15

--

15

  1. Reconnect all SIR components.
  2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

 

Go to Step 2

System OK