Circuit Description
When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Upon passing these tests IGNITION 1, 23 VLR and the deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The SDM monitors the voltages at DRIVER SIDE LOW terminal 3 and PASSENGER SIDE LOW terminal 4 to detect a short to B+ in the inflator module circuits.
Conditions for Setting the DTC
| • | The voltage at PASSENGER SIDE LOW terminal 4 is less than 4.8 volts. |
| • | The voltage at DRIVER SIDE LOW terminal 3 is more than 4.8 volts for 500 milliseconds. |
The CONTINUOUS MONITORING test checks for this DTC. This test occurs when IGNITION 1 is within the normal operating voltage range.
Action Taken When the DTC Sets
| • | The SDM sets a DTC B1025. |
| • | The SDM turns ON the AIR BAG warning lamp. |
Conditions for Clearing the DTC
| • | Current DTC |
| The voltage at DRIVER SIDE LOW terminal 3 is less than 4.8 volts for 500 milliseconds. |
| • | History DTC |
| - | You issue a scan tool CLEAR CODES command. |
| - | Once 250 malfunction free ignition cycles have occurred. |
Diagnostic Aids
A short to B+ in the inflatable restraint steering wheel module circuit can cause an intermittent condition. Inspect CKT 347 and CKT 348 carefully for cutting or chafing. The diagnostic table directs the technician to note the entry value of DRIVER SENSELO. Comparing the value of DRIVER SENSELO can be helpful in determining if an intermittent condition exists.
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 step checks the driver side low voltage that was measured by the inflatable restraint sensing and diagnostic module (SDM).
-
This step isolates the malfunction to one side of the inflatable restraint steering wheel module coil yellow 2-way wiring harness connector.
-
This step determines if there is a malfunctioning inflatable restraint steering wheel module coil or if there is a malfunctioning inflatable restraint steering wheel module.
-
This step checks to see if there is a short to B+ in CKT 347.
-
This step determines if there is a short to B+ in CKT 348 or if there is a malfunctioning SDM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Has the DRIVER SENSELO been read and recorded on the repair order? | -- | -- | ||
Is DRIVER SENSELO more than the specified value? | 4.8 V | |||
Is DRIVER SENSELO more than the specified value? | 4.8 V | |||
5 |
Is the repair complete? | -- | -- | |
6 |
Is the repair complete? | -- | -- | |
Is the measured voltage less than the specified value? | 1.0 V | |||
8 |
Is the repair complete? | -- | -- | |
Use the J 39200 to measure the voltage between terminal 3 and terminal 6 of the SDM wiring harness connector. Is the measured voltage less than the specified value? | 1.0 V | |||
10 |
Is the repair complete? | -- | -- | |
11 | Reconnect all the SIR components, making sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- | |
12 | Use the scan tool to clear all current and history SIR DTCs. Have all current and history SIR DTCs been cleared? | -- | -- |
