Circuit Description
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 Passenger Frontal Low terminal 8 through an internal current sink. |
| • | Connects the Passenger Frontal High terminal 7 to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
| • | Measures the voltage difference between Passenger Frontal High and Passenger Frontal Low. |
| • | Calculates the resistance of the passenger frontal deployment loop using the measured voltage. |
Conditions for Setting the DTC
| • | 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 passenger frontal deployment loop resistance is less than 1.4 ohms. The passenger frontal deployment loop consists of the following components: |
| - | Inflatable restraint IP module. |
| - | Harness wiring of CKT 1403 (WHT/BLK). |
| - | Harness wiring of CKT 1404 (DK GRN/WHT). |
| - | 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.
Action Taken When the DTC Sets
| • | The SDM sets a Diagnostic Trouble Code (DTC). |
| • | The SDM commands the instrument cluster (IPC) to turn ON the AIR BAG warning lamp. |
Conditions for Clearing the MIL/DTC
| • | Current DTC |
| The resistance of the passenger frontal deployment loop is more than 1.4 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.
Diagnostic Aids
The following can cause an intermittent condition:
| • | A short circuit between CKT 1403 and CKT 347. |
| • | A short circuit between CKT 1403 and CKT 348. |
| • | A short circuit between CKT 1403 and CKT 1404. |
| • | A malfunctioning shorting bar on the inflatable restraint IP module 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 in Wiring Systems. When a wire, connector or terminal repair is requested, use J-38125 Terminal Repair Kit and refer to Wiring Repair .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test checks for a short from CKT 347 to CKT 1403.
-
This test checks for proper contact or corrosion of the inflatable restraint IP module connector.
-
This test isolates the malfunction to one side of the inflatable restraint IP module yellow 2-way connector.
-
This test checks for a short from CKT 1403 to CKT 1404.
-
This test checks for a short from CKT 1403 to CKT 348.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | Go to Step 2 | |
Is DTC B1122 also present? | -- | Go to Step 3 | Go to Step 4 | |
3 |
Did you complete the repair? | -- | Go to Step 11 | -- |
Is DTC B1116 current? | -- | Go to Step 5 | Go to Step 11 | |
Is DTC B1116 current? | -- | Go to Step 7 | Go to Step 6 | |
6 | Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement . Did you complete the repair? | -- | Go to Step 11 | -- |
Is the resistance less than the specified value? | OL | Go to Step 8 | Go to Step 9 | |
8 | Repair the short from CKT 1403 to CKT 1404. Refer to Wiring Repair . Did you complete the repair? | -- | Go to Step 11 | -- |
Using J 39200 DMM, measure the resistance between terminals 7 and 9 of the SDM harness connector. Is the resistance less than the specified value? | OL | Go to Step 10 | ||
10 | Repair the short from CKT 1403 to CKT 348. Refer to Wiring Repair . Did you complete the repair? | -- | Go to Step 11 | -- |
11 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | Go to Step 12 | -- |
12 | Clear the SIR DTCs. Have all the SIR DTCs been cleared? | -- | -- |
