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 itself. Next the SDM measures Ignition Positive Voltage and the deployment loop voltages in order to ensure they are within the normal voltage ranges. Then the SDM proceeds with the Resistance Measurement test. During one portion of the Resistance Measurement test, the SDM performs the following actions:
| • | Grounds the Driver Low terminal 3 through an internal current sink |
| • | Connects the Driver High terminal 2 to an internal constant current source. This current produces proportional voltage drops in the deployment loop. |
| • | Measures the voltage difference between Driver High and Driver Low |
| • | Calculates the resistance of the driver 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 driver deployment loop is not shorted to ground. |
| • | The driver deployment loop resistance is less than 1.7 ohms. The driver deployment loop consists of the following components: |
| - | An inflatable restraint steering wheel module |
| - | An inflatable restraint steering wheel module coil |
| - | Harness wiring of CKT 347 (WHT) |
| - | Harness wiring of CKT 348 (DK GRN) |
| - | Connector terminal contact |
The Resistance Measurement test checks for this malfunction. This test only occurs once each ignition cycle when Ignition Positive Voltage 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 driver deployment loop is more than 1.7 ohms and the ignition switch is cycled. |
| • | History DTC |
| - | You issue a scan tool Clear DTCs command. |
| - | 250 ignitions cycles have passed since the last malfunction. |
When you issue a scan tool Clear DTCs command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.
Diagnostic Aids
The following conditions may cause an intermittent condition:
| • | A short circuit between CKT 347 (WHT) and CKT 348 (DK GRN) |
| • | A short circuit between CKT 347 (WHT) and CKT 1403 (WHT/BLK) |
| • | A short circuit between CKT 347 (WHT) and CKT 1404 (DK GRN/WHT) |
| • | A malfunctioning shorting bar on the inflatable restraint steering wheel module connector |
| • | A malfunctioning shorting bar on the inflatable restraint steering wheel module coil steering column connector |
When measurements are requested in this table, use the J 39200 Digital Multimeter with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Intermittents and Poor Connections Diagnosis . When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit. Refer to Wiring Repair .
The diagnostic table directs the technician to note the entry value of Driver Resistance. Comparing the value of Driver Resistance over multiple ignition cycles may be helpful in determining if an intermittent condition exists.
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 isolates the malfunction to one side of the inflatable restraint steering wheel module coil yellow 2-way connector.
-
This test determines whether the malfunction is due to the inflatable restraint steering wheel module or the module coil.
-
This test checks for a short from CKT 347 (WHT) to CKT 348 (DK GRN).
-
This test checks for a short from CKT 347 (WHT) to CKT 1404 (DK GRN/WHT).
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the SIR Diagnostic System Check? | -- | Go to Step 2 | |
Is DTC B1016 also present? | -- | Go to Step 3 | Go to Step 4 | |
3 |
Are the repairs complete? | -- | Go to Step 14 | -- |
4 |
Is Driver Resistance less than the specified value? | 1.7 ohms | Go to Step 6 | Go to Step 5 |
5 |
Are the repairs complete? | -- | Go to Step 14 | -- |
Is Driver Resistance less than the specified value? | 1.7 ohms | Go to Step 10 | Go to Step 7 | |
Is Driver Resistance less than the specified value? | 1.7 ohms | Go to Step 9 | Go to Step 8 | |
8 |
Has the inflatable restraint steering wheel module been replaced? | -- | Go to Step 14 | -- |
9 |
Has the inflatable restraint steering wheel module coil been replaced? | -- | Go to Step 14 | -- |
Is the resistance less than the specified value? | OL | Go to Step 11 | Go to Step 12 | |
11 | Repair a short from CKT 347 (WHT) to CKT 348 (DK GRN). Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 14 | -- |
Measure the resistance from the SDM harness connector terminal 2 to terminal 4. Is the resistance less than the specified value? | OL | Go to Step 13 | ||
13 | Repair a short from CKT 347 (WHT) to CKT 1404 (DK GRN/WHT). Refer to Wiring Repairs in Wiring Systems. Are the repairs complete? | -- | Go to Step 14 | -- |
14 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | Go to Step 15 | -- |
15 | Clear all the SIR DTCs. Have all the SIR DTCs been cleared? | -- | -- |
