For 1990-2009 cars

### Circuit Description

When the inflatable restraint Sensing and Diagnostic Module (SDM) recognizes IGNITION POSITIVE VOLTAGE voltage, applied to terminal 10, is greater than 8.2 volts, the SDM flashes the AIR BAG warning lamp seven times to verify operation. At this time the SDM performs POWER-ON tests followed by the RESISTANCE MEASUREMENT test and the CONTINUOUS MONITORING tests. Upon detection of a malfunction, the SDM sets a current Diagnostic Trouble Code (DTC) and illuminates the AIR BAG warning lamp. The SDM will clear current DTCs and preserve them in a history file when:

• | The malfunction is no longer detected.

• | The ignition switch is cycled.

This does not include DTCs B1018, B1024, B1051, B1053, and B1071. DTCs B1018, B1024, B1051, B1053 are latched codes. You cannot clear a latched code. DTC B1071 may not clear after you issue a clear codes command.

Important: Repair the malfunction that set the DTC before you replace the SDM.

### Test Description

The numbers below refer to the step numbers on the diagnostic table:

1. This test confirms a circuit malfunction. If no current malfunction is occurring (history DTC set), refer to the diagnostic aids for the appropriate DTC table as indicated through the scan tool. Do not replace the inflatable restraint Sensing and Diagnostic Module (SDM) for a history DTC other than DTC B1071.

2. This test checks for a malfunction introduced into the SIR system during the diagnostic process. It is unlikely that a malfunctioning SDM would cause a new malfunction to occur during this process.

3. When you have found all circuitry outside the SDM to operate properly, as indicated by the appropriate diagnostic table, replace the SDM.

This table assumes that the SIR Diagnostic System Check and either a symptom table or a Diagnostic Trouble Code table diagnosis has been performed. When all circuitry outside the inflatable restraint Sensing and Diagnostic Module (SDM) has been found to operate properly, as indicated by the appropriate diagnostic table, and the symptom or DTC remains current, the following diagnostic procedures must be performed to verify the need for SDM replacement.

#### Integrity Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Were you sent here from a symptom table or a Diagnostic Trouble Code (DTC) table? | -- | Go to Step 2 | Go to SIR Diagnostic System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Reconnect all the SIR components, make sure all the components are properly mounted.
3. Make sure the ignition switch has been in the OFF position for at least 30 seconds.
4. Note the AIR BAG warning lamp while turning the ignition switch to the RUN position.

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

--

Go to Step 7

Go to Step 3

3 | Using the scan tool, request the SIR DTC display. Is the same symptom or DTC occurring as when the SIR Diagnostic System Check was first performed? | -- | Go to Step 4 | Go to the appropriate DTC table
4 |

1. Clear the SIR DTCs.
2. Turn the ignition switch to the OFF position for at least 30 seconds.
3. Note the AIR BAG warning lamp while turning the ignition switch to the RUN position.

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

--

System OK

Go to Step 5

5 |

1. Turn the ignition switch to the OFF position.
2. Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Has the SDM been replaced?

--

Go to Step 6

--

6 | Reconnect all the SIR system components, and make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | Go to SIR Diagnostic System Check | --
7 | Clear the SIR DTCs. Have the SIR DTCs been cleared? | -- | Go to SIR Diagnostic System Check | --