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 voltage to make sure it is within its respective normal voltage range. Then the SDM proceeds with the DEPLOYMENT LOOP CONTINUITY test. During the DEPLOYMENT LOOP CONTINUITY test, the SDM measures the voltage difference between DRIVER SIDE HIGH and DRIVER SIDE LOW.
Conditions for Setting the DTC
| • | The voltage difference between DRIVER SIDE HIGH terminal 2 and DRIVER SIDE LOW terminal 3 is more than or equal to 400 millivolts. |
| • | The malfunction must be 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 lamp. |
Conditions for Clearing the DTC
| • | Current DTC |
| The voltage difference between DRIVER SIDE HIGH terminal 2 and DRIVER SIDE 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 can 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 could also set this DTC. To test for a bad inflatable restraint steering wheel module coil, clear the DTCs, then turn the steering wheel back and forth with the ignition switch in the ON position. If the AIR BAG warning lamp comes ON and DTC B1026 has set again, it is likely the inflatable restraint steering wheel module coil is malfunctioning.
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 voltage difference measured by the inflatable restraint sensing and diagnostic module.
-
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 inflatable restraint sensing and diagnostic module 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 . Are the repairs 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 . Are the repairs complete? | -- | -- | |
8 |
Is the DRIVER VDIF less than the specified value? | 400 mV | ||
9 |
Are the repairs complete? | -- | -- | |
Is the DRIVER VDIF less than the specified value? | 400 mV | |||
Is the DRIVER VDIF less than the specified value? | 400 mV | |||
12 |
Are the repairs complete? | -- | -- | |
13 |
Are the repairs complete? | -- | -- | |
Is the connector damaged or corroded? | -- | |||
15 | Replace the SDM harness connector. Refer to Wiring Repair . Are the repairs 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 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 | |||
20 | Repair the high resistance condition in CKT 347. Are the repairs complete? | -- | -- | |
Measure the resistance from the SDM harness connector terminal 3 to the 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. Are the repairs 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? | -- | -- |
