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 Positive Voltage, 23VLR 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 LOW terminal 9 and PASSENGER LOW terminal 8 to detect shorts to voltage in the inflator module circuits.
Conditions for Setting the DTC
The voltage at DRIVER LOW terminal 9 OR PASSENGER LOW terminal 8 is more than 4.0 volts for 500 milliseconds.
The following tests check for this DTC. These tests occur when Ignition Positive Voltage is within the normal operating voltage range.
| • | POWER-ON-When 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 commands the Instrument Panel Cluster (IPC) to turn ON the AIR BAG warning lamp. |
Conditions for Clearing the MIL/DTC
| • | The voltage measured at DRIVER LOW and PASSENGER LOW is below 4.0 volts for 500 milliseconds. |
| • | The ignition switch is turned OFF. |
| • | DTC B1171 WILL REMAIN CURRENT. |
Diagnostic Aids
A short-to-voltage in the inflatable restraint steering wheel module circuit or the passenger inflator module circuit can cause an intermittent condition. Moving wires while monitoring DRIVER SENSELO and PASSENGER SENSELO may help to locate the fault. Inspect CKT 347, CKT 348, 1403, and 1404 carefully for cutting or chafing. The diagnostic table directs the technician to note the entry value of DRIVER SENSELO and PASSENGER SENSELO. Noting the value of DRIVER SENSELO and PASSENGER SENSELO during diagnosis can be helpful in determining if an intermittent condition exists. 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, monitor DRIVER SENSELO while you turn the steering wheel back and forth with the ignition switch in the RUN position. If DRIVER SENSELO changes while you are turning the steering wheel, 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 driver low voltage measured by the inflatable restraint Sensing and Diagnostic Module (SDM) and if the malfunction is occurring now.
-
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 determines whether the malfunction is in CKT 347.
-
This test determines whether the malfunction is in CKT 348.
-
This test isolates the malfunction to one side of the inflatable restraint IP module, yellow 2-way connector.
-
This test determines whether the malfunction is in CKT 1403.
-
This test determines whether the malfunction is in CKT 1404.
Notice: When DTC B1125 has been set it is necessary to replace the inflatable restraint Sensing and Diagnostic Module (SDM). Setting DTC B1125 will also cause DTC B1171 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC B1171 will remain current. Make sure that the short to voltage condition is repaired prior to installing a replacement SDM to avoid damaging the SDM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
2 |
Is DRIVER SENSELO more than the specified value? | 4.0 V | ||
Is DRIVER SENSELO more than the specified value? | 4.0 V | |||
Is DRIVER SENSELO more than the specified value? | 4.0 V | |||
5 |
Are the repairs complete? | -- | -- | |
6 |
Are the repairs complete? | -- | -- | |
7 |
Is the voltage reading less than the specified value? | 1 V | ||
8 | Repair a short-to-voltage condition in CKT 347. Are the repairs complete? | -- | -- | |
9 | Measure the voltage on the SDM harness connector from terminal 9 to terminal 18 (ground). Is the voltage reading less than the specified value? | 1 V | ||
10 | Repair a short-to-voltage condition in CKT 348. Are the repairs complete? | -- | -- | |
11 |
Is PASSENGER SENSELO more than the specified value? | 4.0 V | ||
12 |
Are the repairs complete? | -- | -- | |
13 |
Is the voltage less than the specified value? | 1 V | ||
14 | Repair a short-to-voltage condition in CKT 1404. Are the repairs complete? | -- | -- | |
15 | Measure the voltage on the SDM harness connector from terminal 7 to terminal 18 (ground). Is the voltage less than the specified value? | 1 V | ||
16 | Repair a short-to-voltage condition in CKT 1403. Are the repairs complete? | -- | -- | |
17 | An intermittent short-to-voltage condition caused DTC B1125 to set. Use the Diagnostic Aids for DTC B1125 and this table to find the intermittent short to voltage. Has the intermittent short to voltage been found and repaired? | -- | -- | |
18 |
Have all the SIR components been reconnected and properly mounted? | 4.0 V | -- |
