Circuit Description
When you first turn the ignition switch to the ON position, the inflatable restraint Sensing and Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. Next the SDM measures IGNITION 1 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 3 through an internal current sink. |
| • | Connects the PASSENGER SIDE 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 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 the YEL/RED wire. |
| - | Harness wiring the YEL wire. |
| - | 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 DTC
| • | Clear the Current DTC when the resistance of the passenger deployment loop is less than 3.0 ohms and the ignition switch is cycled. |
| • | Clear the History DTC under the following conditions: |
| - | 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.
Diagnostic Aids
A poor connection can cause an intermittent condition. Check the following for a poor connection:
| • | The inflatable restraint IP module harness connector terminal 1 and terminal 2 |
| • | The SDM terminal 4 and terminal 3. |
| • | The wire to terminal connections in the YEL/RED wire. |
| • | The wire terminal connections in the YEL wire. |
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 in this section.
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 and/or corrosion of the yellow connector.
-
This test isolates the malfunction to one side of the inflatable restraint IP module yellow connector. This is done by substituting the known good resistance of the load tool, then observing if the malfunction is still present.
-
This test checks for proper contact and/or corrosion of the SDM connector.
-
This test determines if the malfunction is in the YEL/RED wire.
-
This test determines if the malfunction is in the YEL wire.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Did you read and record PASSENGER RESISTANCE on the repair order? | -- | -- | ||
Are the terminals damaged or corroded? | -- | |||
4 | Replace the inflatable restraint IP module harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair in this section. Did you replace the inflatable restraint IP module harness connector? | -- | -- | |
5 | Check for proper connection at terminal 1 and terminal 2 on the inflatable restraint IP module connector. Are the terminals damaged or corroded? | -- | ||
6 | Check for proper connection at terminal B1 and terminal B2 on the inflatable restraint IP module connector. Are the terminals damaged or corroded? | -- | ||
7 | Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement in this section. Did you replace the inflatable restraint IP module? | -- | -- | |
8 |
Is PASSENGER RESISTANCE more than the specified value? | 3.0 ohms | ||
9 |
Did you replace the inflatable restraint IP module harness connector? | -- | -- | |
Is PASSENGER RESISTANCE more than the specified value? | 3.0ohms | |||
11 |
Did you replace the inflatable restraint IP module? | -- | -- | |
Is the SDM harness connector damaged or corroded? | -- | |||
13 | Replace the SDM harness connector. Refer to SIR Connector (Plastic Body and Terminal Metal Pin) Repair portion of Wiring Repair in this section. Did you replace the SDM harness connector? | -- | -- | |
14 | Check for proper connection at terminal 4 and terminal 3 on the SDM. Are the SDM terminals damaged or corroded? | -- | ||
15 | Check for proper connection at terminal 4 and terminal 3 on the SDM. Are the SDM terminals damaged or corroded? | -- | ||
16 | Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement in this section. Did you replace the SDM? | -- | -- | |
Zero the J 39200 and measure the resistance from the SDM harness connector terminal 4 to the inflatable restraint IP module harness connector terminal B2. Is the resistance reading within the specified values? | 0-0.5ohms | |||
18 | Repair high resistance in the YEL/RED wire. Is the circuit repair complete? | -- | -- | |
Reconnect all the SIR system components. Confirm that all the components are properly mounted. Are all the SIR components reconnected and properly mounted? | -- | Go to Integrity Check | -- | |
20 | Repair high resistance in the YEL wire. Is the circuit repair complete? | -- | -- | |
21 | Reconnect all the SIR components. Confirm that all components are properly mounted. Are all the SIR components been reconnected and properly mounted? | -- | -- | |
22 | Clear the SIR diagnostic trouble codes. Did you clear the SIR diagnostic trouble codes? | -- | -- |
