When you first turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures Ignition 1 and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the SDM proceeds with the Resistance Measurement test. During one portion of the Resistance Measurement test, the SDM does the following:
• | Grounds the Driver Frontal Low terminal 9 through an internal current sink. |
• | Connects the Driver Frontal High terminal 10 to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
• | Measures the voltage difference between Driver Frontal High and Driver Frontal Low. |
• | Calculates the resistance of the driver frontal deployment loop using the measured voltage. |
• | The driver and passenger frontal and pretensioner deployment loops are not open. |
• | The driver and passenger frontal deployment loops are not shorted to voltage. |
• | The driver and passenger frontal deployment loops are not shorted to ground. |
• | The driver frontal deployment loop resistance is less than 1.7 ohms. The driver frontal deployment loop consists of the following components: |
- | Inflatable restraint steering wheel module. |
- | Inflatable restraint steering wheel module coil. |
- | Harness wiring of CKT 347. |
- | Harness wiring of CKT 348. |
- | Connector terminal contact. |
The Resistance Measurement test checks for this malfunction. This test only occurs once each ignition cycle when IGNITION 1 is within the normal operating voltage range.
• | The SDM sets a Diagnostic Trouble Code (DTC). |
• | The SDM commands the instrument cluster (IPC) to turn ON the AIR BAG warning lamp. |
• | Current DTC-The resistance of the driver frontal deployment loop is more than 1.7 ohms and the ignition switch is cycled. |
• | History DTC |
- | You issue a scan tool Clear DTCs command. |
- | Once 250 malfunction free ignition cycles have occurred. |
When you issue a scan tool Clear DTCs command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.
The following can cause an intermittent condition:
• | A short circuit between CKT 347 and CKT 348. |
• | A short circuit between CKT 347 and CKT 1403. |
• | A short circuit between CKT 347 and CKT 1404. |
• | A malfunctioning shorting bar on the inflatable restraint steering wheel module connector. |
• | A malfunctioning shorting bar on the inflatable restraint steering wheel module coil steering column connector. |
When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to General Electrical Diagnosis Procedures in Wiring Systems. When a wire, connector or terminal repair is requested, use J-38125 Terminal Repair Kit and refer to Wiring Repair .
The numbers below refer to the step numbers on the diagnostic table:
This test checks for a short from the Passenger Frontal High circuit to the Driver Frontal High circuit.
This test isolates the malfunction to one side of the inflatable restraint steering wheel module coil yellow 2-way connector.
This test determines whether the malfunction is due to the inflatable restraint steering wheel module or the module coil.
This test checks for a short from CKT 347 to CKT 348.
This test checks for a short from CKT 347 to CKT 1404.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Is DTC B1116 also present? | -- | |||
3 |
Have the repairs been completed? | -- | -- | |
Is DTC B1122 current? | -- | |||
Is DTC B1122 current? | ---- | |||
6 |
Is DTC B1122 current? | ---- | ||
7 |
Have the repairs been completed? | -- | -- | |
8 |
Have the repairs been completed? | -- | -- | |
9 |
Is the resistance reading less than the specified value? | OL | ||
10 | Repair a short from CKT 347 to CKT 348. Refer to Wiring Repair . Have the repairs been completed? | -- | -- | |
11 | Using J 39200 DMM, measure the resistance between terminals 8 and 10 of the SDM harness connector. Is the resistance reading less than the specified value? | OL | ||
12 | Repair a short from CKT 347 to CKT 1404. Refer to Wiring Repair . Have the repairs been completed? | -- | -- | |
13 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
14 | Clear all the SIR DTCs. Refer to Diagnostic Trouble Code (DTC) Clearing in Wiring Systems. Have all the SIR DTCs been cleared? | -- | -- |