Circuit Description
When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures IGNITION 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 Side Low terminal 14 through an internal current sink. |
| • | Connects the Passenger Side High terminal 13 to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
| • | Measures the voltage difference between Passenger Side High and Passenger Side Low. |
| • | Calculates the resistance of the driver side air bag deployment loop using the measured voltage. |
Conditions for Setting the DTC
| • | The driver and passenger side air bag deployment loops are not open. |
| • | The driver and passenger side air bag deployment loops are not shorted to voltage. |
| • | The driver side air bag deployment loop is not shorted to ground. |
| • | The driver side air bag deployment loop resistance is less than 1.52 ohms. The passenger side air bag deployment loop consists of the following components: |
| - | Inflatable restraint driver seat module. |
| - | Harness wiring of CKT 2137. |
| - | Harness wiring of CKT 2138. |
| - | Connector terminal contact. |
The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs once each ignition cycle when IGNITION is within the normal operating voltage range.
Action Taken When the DTC Sets
| • | The SDM sets a diagnostic trouble code. |
| • | The SDM turns ON the AIR BAG warning lamp. |
Conditions for Clearing the DTC
| • | Current DTC |
| The resistance of the driver side air bag deployment loop is more than 1.72 ohms and the ignition switch is cycled. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | Once 250 malfunction free ignition cycles have occurred. |
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
The following can cause an intermittent condition:
| • | A short circuit between CKT 2137 and CKT 2138. |
| • | A malfunctioning shorting bar on the inflatable restraint passenger seat module connector. |
The diagnostic table directs the technician to note the entry value of LH SIDE AIR BAG RESIST. Comparing the value of LH SIDE AIR BAG RESIST. over multiple ignition cycles can be helpful in determining if an intermittent condition exists.
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 determines the deployment loop resistance measured by the inflatable restraint sensing and diagnostic module (SDM).
-
This test checks for proper contact or corrosion of the yellow 2-way connector.
-
This test isolates the malfunction to one side of the inflatable restraint front side impact module (LH) yellow 2-way connector.
-
This test checks for proper contact or corrosion of the SDM connector.
-
This test checks for a short between CKT 2137 and CKT 2138.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Has LH SIDE AIR BAG RESIST. been read and recorded on the repair order? | -- | -- | ||
Are the terminals damaged or corroded? | -- | |||
4 | Replace the inflatable restraint front side impact module (LH) yellow 2-way body harness connector. Refer to Wiring Repair . Are the repairs complete? | -- | -- | |
5 | Check for proper connection at terminals A and B on the inflatable restraint front side impact module (LH) yellow 2-way connector. Are the terminals damaged or corroded? | -- | ||
6 | Check for proper connection at terminals A and B on the inflatable restraint front side impact module (LH) yellow 2-way connector. Are the terminals damaged or corroded? | -- | ||
7 | Replace the inflatable restraint front side impact module (LH). Refer to Driver and Passenger Seat Side Inflatable Restraint Module Replacement . Is the replacement complete? | -- | -- | |
8 |
Is LH SIDE AIR BAG RESIST. less than the specified value? | 1.5 ohms | ||
9 |
Are the repairs complete? | -- | -- | |
Is LH SIDE AIR BAG RESIST. less than the specified value? | 1.5 ohms | |||
11 |
Is the replacement complete? | -- | -- | |
Is the harness connector damaged or corroded? | -- | |||
13 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM) harness connector. Refer to Wiring Repair . Are the repairs complete? | -- | -- | |
14 | Check for proper connection at terminals 10 and 11 on the SDM. Are the terminals damaged or corroded? | -- | ||
15 | Check for proper connection at terminals 10 and 11 on the SDM. Are the terminals damaged or corroded? | -- | ||
16 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Are the repairs complete? | -- | -- | |
Is the resistance reading within the specified values? | 0-0.5 ohms | Go to Integrity Check | ||
18 | Repair the short between CKT 2137 and CKT 2138. Are the repairs complete? | -- | -- | |
19 | Reconnect all the SIR components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
20 | Clear all the SIR DTCs. Have all the DTCs been cleared? | -- | -- |
