Circuit Description
When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) perform tests to diagnose critical malfunctions within the module. Next the SDM measures Ignition Positive Voltage 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 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 more than 3.0 ohms. |
| • | The passenger frontal deployment loop consists of the following items: |
| - | An inflatable restraint IP module. |
| - | A harness wiring of CKT 1403. |
| - | A harness wiring of CKT 1404. |
| - | A connector terminal contact. |
The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs once each ignition cycle when the ignition positive voltage is within the normal operating voltage range.
Action Taken When the DTC Sets
| • | The SDM sets a diagnostic trouble code. |
| • | The SDM commands the instrument panel cluster 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 less than 3.0 ohms and the ignition switch is cycled. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | 250 malfunction free ignition cycles occur. |
When you issue a scan tool CLEAR CODES command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.
Diagnostic Aids
A poor connection may cause an intermittent condition. Inspect the following items for a poor connection:
| • | The inflatable restraint IP module harness connector terminals A and B. |
| • | The SDM terminals 7 and 8. |
| • | The wire to terminal connections in CKT 1403. |
| • | The wire to terminal connections in CKT 1404. |
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 Intermittents and Poor Connections . 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 proper contact or corrosion of the inflatable restraint IP module yellow 2-way connector.
-
This test isolates the malfunction to one side of the inflatable restraint IP module yellow 2-way connector.
-
This test checks for proper contact or corrosion of the SDM connector.
-
This test determines whether the malfunction is in CKT 1403.
-
This test determines whether the malfunction is in CKT 1404.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Are the terminals damaged or corroded? | -- | |||
3 | Replace the inflatable restraint IP module yellow 2-way IP harness connector. Refer to Wiring Repair . Have the repairs been completed? | -- | -- | |
4 | Check for proper connection at terminals A and B on the inflatable restraint IP module yellow 2-way connector. Are the terminals damaged or corroded? | -- | ||
5 | Check for proper connection at terminals A and B on the inflatable restraint IP module yellow 2-way connector. Are the terminals damaged or corroded? | -- | ||
6 | Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement . Have the repairs been completed? | -- | -- | |
7 |
Is DTC B1115 set as a current DTC? | -- | ||
8 |
Have the repairs been completed? | -- | -- | |
Is DTC B1115 set as a current DTC? | -- | |||
10 |
Have the repairs been completed? | -- | -- | |
Is the harness connector damaged or corroded? | -- | |||
12 | Replace the inflatable restraint sensing and diagnostic module (SDM) harness connector. Refer to Connector Repairs . Have the repairs been completed? | -- | -- | |
13 | Check for proper connection at terminals 8 and 7 on the SDM. Are the terminals damaged or corroded? | -- | ||
14 | Check for proper connection at terminals 8 and 7 on the SDM. Are the terminals damaged or corroded? | -- | ||
15 | Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Have the repairs been completed? | -- | -- | |
Using J 39200 DMM, measure the resistance from the SDM harness connector terminal 7 to the inflatable restraint IP module yellow 2-way harness connector terminal A. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
17 | Repair the high resistance condition in CKT 1403. Have the repairs been completed? | -- | -- | |
Using J 39200 DMM, measure the resistance from the SDM harness connector terminal 8 to the inflatable restraint IP module yellow 2-way harness connector terminal B. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
19 | Repair the high resistance condition in CKT 1404. Have the repairs been completed? | -- | -- | |
20 | Reconnect all the SIR components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
21 | Clear all the SIR DTCs. Have all the DTCs been cleared? | -- | -- |
