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 the ignition positive voltage in order to ensure that the voltage is within the respective normal voltage range. The SDM proceeds with the deployment loop continuity test. During the deployment loop continuity test, the SDM measures the voltage difference between the DRIVER HIGH and the DRIVER LOW.
Conditions for Setting the DTC
| • | The voltage difference between the DRIVER HIGH terminal 2 and DRIVER LOW terminal 3 is more than or equal to 400 millivolts. |
| • | Ensure that the malfunction is present for at least 500 milliseconds during one of the following tests: |
| - | Deployment loop continuity |
| - | If the malfunction is detected in this test, the resistance measurement test will not be performed. |
| - | Continuous monitoring |
Action Taken When the DTC Sets
| • | The SDM sets a Diagnostic Trouble Code. |
| • | The SDM turns ON the AIR BAG Warning Indicator. |
Conditions for Clearing the MIL/DTC
| • | Current DTC |
| The voltage difference between DRIVER HIGH terminal 2 and DRIVER LOW terminal 3 is less than 400 millivolts for 500 milliseconds. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | Once 250 malfunction free ignition cycles have occurred. |
Diagnostic Aids
The following conditions may cause an intermittent condition:
| • | A poor connection at the inflatable restraint steering wheel module column connector terminals A and B |
| • | A poor connection at the upper inflatable restraint steering wheel coil connector terminals A and B |
| • | A poor connection at the SDM terminals 2 and 3 |
| • | An open in CKT 347 |
| • | An open in CKT 348 |
An intermittent open in the inflatable restraint steering wheel module coil may also set this DTC. Clear the DTCs in order to test for a bad inflatable restraint steering wheel module coil, then turn the steering wheel back and forth with the ignition switch in the RUN position. If the AIR BAG warning lamp turns ON and DTC B1026 has set again, the inflatable restraint steering wheel module coil is malfunctioning.
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 .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
This test determines the deployment loop voltage difference measured by the 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 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 proper contact or corrosion of the SDM connector.
-
This test determines whether the malfunction is in CKT 347.
-
This test determines whether the malfunction is in CKT 348.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Has the DRIVER VDIF been read and recorded on the repair order? | -- | -- | ||
Are the terminals damaged or corroded? | -- | |||
4 | Replace the inflatable restraint steering wheel module yellow 2-way harness connector. Refer to Wiring Repair . Is the repair complete? | -- | -- | |
5 | Check for proper connection at terminals A and B on the coil side of the connector. Are the terminals damaged or corroded? | -- | ||
6 | Check for proper connection at terminals A and B on the coil side of the connector. Are the terminals damaged or corroded? | -- | ||
7 | Replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement . Is the repair complete? | -- | -- | |
8 |
Is DRIVER VDIF less than the specified value? | 400 mV | ||
9 |
Is the repair complete? | -- | -- | |
Is DRIVER VDIF less than the specified value? | 400 mV | |||
Is DRIVER VDIF less than the specified value? | 400 mV | |||
12 |
Is the repair complete? | -- | -- | |
13 |
Is the repair complete? | -- | -- | |
Is the connector damaged or corroded? | -- | |||
15 | Replace the SDM harness connector. Refer to Connector Repairs in Wiring Ssytems. Is the repair complete? | -- | -- | |
16 | Check for proper connection at terminals 2 and 3 of the SDM. Are the terminals damaged or corroded? | -- | ||
17 | Check for proper connection at terminals 2 and 3 of the SDM. Are the terminals damaged or corroded? | -- | ||
18 | Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Is the repair complete? | -- | -- | |
Using J 39200 DMM, measure the resistance between SDM harness connector terminal 2 and inflatable restraint steering wheel module yellow 2-way harness connector terminal A. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
20 | Repair the high resistance condition in CKT 347. Is the repair complete? | -- | -- | |
Using J 39200 DMM, measure the resistance between SDM harness connector terminal 3 and inflatable restraint steering wheel module yellow 2-way harness connector terminal B. Is the resistance reading within the specified values? | 0-0.5 ohms | |||
22 | Repair the high resistance condition in CKT 348. Is the repair complete? | -- | -- | |
23 | Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
24 | Clear all the SIR DTCs. Have all the SIR DTCs been cleared? | -- | -- |
