Circuit Description
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. The SDM measures IGNITION 1 and the deployment loop voltages in order to ensure that the voltages are within the respective normal voltage ranges. The SDM proceeds with the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the SDM performs the following actions:
| • | Grounds the PASSENGER SIDE LOW terminal 4 through an internal current sink |
| • | Connects the PASSENGER SIDE HIGH terminal 1 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 passenger deployment loop using the measured voltage |
Conditions for Setting the DTC
| • | 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 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 1 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 MIL/DTC
| • | 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.
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 1 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 PASSENGER RESISTANCE. Comparing the value of PASSENGER RESISTANCE over multiple ignition cycles may be helpful in determining if an intermittent condition exists.
When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.
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 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 the PASSENGER RESISTANCE 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 . 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 . Are the repairs complete? | -- | -- | |
8 |
Is the PASSENGER RESISTANCE more than the specified value? | 3.0 ohms | ||
9 |
Are the repairs complete? | -- | -- | |
Is the PASSENGER RESISTANCE more than the specified value? | 3.0 ohms | |||
11 |
Are the repairs 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 1 and 4 on the SDM. Are the terminals damaged or corroded? | -- | ||
15 | Check for proper connection at terminals 1 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? | -- | -- |
