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 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 Frontal Low terminal 3 through an internal current sink. |
• | Connects the Passenger Frontal High terminal 4 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 deployment loop using the measured voltage. |
• | The driver and passenger frontal air bag deployment loops are not open. |
• | The driver and passenger frontal air bag deployment loops are not shorted to voltage. |
• | The passenger frontal air bag deployment loop is not shorted to ground. |
• | The passenger frontal air bag deployment loop resistance is more than 3.0 ohms. The passenger deployment loop consists of the following components: |
- | Inflatable restraint IP module. |
- | Harness wiring of CKT 1403. |
- | Harness wiring of CKT 1404. |
- | 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.
• | The SDM sets a Diagnostic Trouble Code. |
• | The SDM turns ON the AIR BAG warning lamp. |
• | Current DTC |
The resistance of the passenger deployment loop is less than 3.0 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.
A poor connection can cause an intermittent condition. Check the following for a poor connection:
• | The inflatable restraint IP module harness connector terminals A and B. |
• | The SDM terminals 3 and 4. |
• | The wire to terminal connections in CKT 1403. |
• | The wire to terminal connections in CKT 1404. |
The diagnostic table directs the technician to note the entry value of PASS. FRONTAL RESIST.. Comparing the value of PASS. FRONTAL 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 .
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 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? | -- | ||
Has PASS. FRONTAL RESIST. been read and recorded on the repair order? | -- | -- | ||
Are the terminals damaged or corroded? | -- | |||
4 | Replace the inflatable restraint IP module yellow 2-way IP harness connector. Refer to Wiring Repair in this section. Are the repairs complete? | -- | -- | |
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 | 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? | -- | ||
7 | Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement . Has the inflatable restraint IP module been replaced? | -- | -- | |
8 |
Is PASS. FRONTAL RESIST. more than the specified value? | 3.0 ohms | ||
9 |
Are the repairs complete? | -- | -- | |
Is PASS. FRONTAL RESIST. more than the specified value? | 3.0 ohms | |||
11 |
Has the inflatable restraint IP module been replaced? | -- | -- | |
Is the harness connector damaged or corroded? | -- | |||
13 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM) harness connector. Refer to Wiring Repair in this section. Are the repairs complete? | -- | -- | |
14 | Check for proper connection at terminals 3 and 4 on the SDM. Are the terminals damaged or corroded? | -- | ||
15 | Check for proper connection at terminals 3 and 4 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 | |||
18 | Repair the high resistance condition in CKT 1403. Are the repairs complete? | -- | -- | |
Is the resistance reading within the specified values? | 0-0.5 ohms | Go to Integrity Check | ||
20 | Repair the high resistance condition in CKT 1404. Are the repairs complete? | -- | -- | |
21 | Reconnect all the SIR components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
22 | Clear all the SIR DTCs. Have all the DTCs been cleared? | -- | -- |