Circuit Description
When you first turn the ignition switch to the RUN position, the supplemental 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 DRIVER SIDE LOW terminal 3 through an internal current sink. |
| • | Connects the DRIVER SIDE 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 SIDE HIGH and DRIVER SIDE 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 ohm. The driver deployment loop consists of the following components: |
| - | Supplemental restraint steering wheel module. |
| - | Supplemental restraint steering wheel module coil. |
| - | Harness wiring of CKT 347. |
| - | Harness wiring of CKT 348. |
| - | 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
| • | Current DTC--The resistance of the driver deployment loop is more than 1.7 ohm 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
The following can cause an intermittent condition:
| • | A short circuit between CKT 347 and CKT 348. |
| • | A short circuit between CKT 347 and CKT 1403. |
| • | A short circuit between CKT 347 and CKT 1404. |
| • | A malfunctioning shorting bar on the supplemental restraint steering wheel module connector. |
| • | A malfunctioning shorting bar on the supplemental restraint steering wheel module coil steering column connector. |
The diagnostic table directs the technician to note the entry value of DRIVER RESISTANCE. Comparing the value of DRIVER RESISTANCE 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 an inspection 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 .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test determines the deployment loop resistance measured by the supplemental restraint sensing and diagnostic module (SDM).
-
This test isolates the malfunction to one side of the supplemental restraint steering wheel module coil yellow 2-way connector.
-
This test determines whether the malfunction is due to the supplemental restraint steering wheel module or the module coil.
-
This test inspects for a short from CKT 347 to CKT 348.
-
This test inspects for a short from CKT 347 to CKT 1404.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SRS Diagnostic System Check performed? | -- | ||
Is DTC B1016 also present? | -- | |||
3 |
Is the repair complete? | -- | -- | |
4 |
Is DRIVER RESISTANCE less than the specified value? | 1.7 ohms | ||
5 |
Is the repair complete? | -- | -- | |
Is DRIVER RESISTANCE less than the specified value? | 1.7 ohms | |||
Is DRIVER RESISTANCE less than the specified value? | 1.7 ohms | |||
8 |
Is the repair complete? | -- | -- | |
9 |
Is the repair complete? | -- | -- | |
Is the resistance reading less than the specified value? | OL | |||
11 | Repair a short from CKT 347 to CKT 348. Is the repair complete? | -- | -- | |
Measure the resistance from the SDM harness connector terminal 2 to terminal 4. Is the resistance reading less than the specified value? | OL | |||
13 | Repair a short from CKT 347 to CKT 1404. Is the repair complete? | -- | -- | |
14 |
Have all the SRS components been reconnected and properly mounted? | -- | -- | |
15 | Clear all the SRS DTCs. Have all the SRS DTCs been cleared? | -- | -- |
