When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests in order to diagnose critical malfunctions within the module. Next the SDM measures the ignition positive voltage and the deployment loop voltages in order to ensure that the voltages are within their respective normal voltage ranges. The SDM proceeds with the resistance measurement test. During 1 portion of the resistance measurement test, the SDM performs the following functions:
• | Grounds the PASSENGER LOW terminal 4 through an internal current sink |
• | Connects the PASSENGER HIGH terminal 1 to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
• | Measures the voltage difference between the PASSENGER HIGH and the PASSENGER LOW |
• | Calculates the resistance of the passenger deployment loop using the measured voltage |
• | The driver and passenger deployment loops are not open. |
• | The driver and passenger deployment loops are not shorted to voltage. |
• | The passenger deployment loop is not shorted to ground. |
• | The passenger deployment loop resistance is less than 1.4 ohms. The passenger deployment loop consists of the following components: |
- | An Inflatable restraint I/P module |
- | Harness wiring of CKT 1403 |
- | Harness wiring of CKT 1404 |
- | Connector terminal contact |
The resistance measurement test inspects for this malfunction. This test only occurs once each ignition cycle when the ignition positive voltage is within the normal operating voltage range.
• | The SDM sets a diagnostic trouble code. |
• | The SDM turns ON the AIR BAG Warning Indicator. |
• | Current DTC |
The resistance of the passenger deployment loop is more than 1.4 ohms and the ignition switch is cycled. |
• | History DTC |
- | You issue a scan tool CLEAR CODES command. |
- | 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.
The following conditions may 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 I/P module connector |
The diagnostic table directs the technician in order to note the entry value of the PASSENGER RESISTANCE. Comparing the value of the PASSENGER RESISTANCE over multiple ignition cycles may 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 .
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 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 inflatable restraint IP module 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? | -- | ||
Is DTC B1022 also present? | -- | |||
3 |
Is the repair complete? | -- | -- | |
4 |
Is PASSENGER RESISTANCE less than the specified value? | 1.4 ohms | ||
5 |
Is the repair complete? | -- | -- | |
Is PASSENGER RESISTANCE less than the specified value? | 1.4 ohms | |||
7 |
Is the repair complete? | -- | -- | |
Is the resistance less than the specified value? | OL | |||
9 |
Is the repair complete? | -- | -- | |
Using J 39200 DMM, measure the resistance between SDM harness connector terminals 1 and 3. Is the resistance less than the specified value? | OL | |||
11 | Repair the short from CKT 1403 to CKT 348. Is the repair complete? | -- | -- | |
12 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
13 | Clear the SIR DTCs. Have all the SIR DTCs been cleared? | -- | -- |