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. Upon passing these tests, the ignition positive voltage, 23 VLR and the deployment loop voltages are measured in order to ensure that the voltages are within the respective normal voltage ranges. The SDM monitors the voltages at the DRIVER LOW terminal 9 and the PASSENGER LOW terminal 8 in order to detect shorts to voltage in the inflator module circuits.
Conditions for Setting the DTC
The voltage at DRIVER LOW terminal 9 or the PASSENGER LOW terminal 8 is more than 4.0 volts for 500 milliseconds.
The following tests inspects 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 cluster to turn ON the AIR BAG warning lamp. |
Conditions for Clearing the MIL/DTC
| • | The voltage measured at the DRIVER LOW and the 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 may cause an intermittent condition. Moving wires while monitoring the DRIVER SENSELO and the PASSENGER SENSELO may help locate the fault. Carefully inspect the following circuits for cutting or chafing:
| • | CKT 347 |
| • | CKT 348 |
| • | CKT 1403 |
| • | CKT 1404 |
The diagnostic table directs the technician to note the entry value of the DRIVER SENSELO and the PASSENGER SENSELO. Noting the value of the DRIVER SENSELO and the PASSENGER SENSELO during diagnosis may 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:
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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.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
|
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. | ||||
1 | Was the SIR Diagnostic System Check performed? | -- | Go to Step 2 | |
2 |
Is the DRIVER SENSELO more than the specified value? | 4.0 V | Go to Step 3 | Go to Step 17 |
Is the DRIVER SENSELO more than the specified value? | 4.0 V | Go to Step 7 | Go to Step 4 | |
Is the DRIVER SENSELO more than the specified value? | 4.0 V | Go to Step 6 | Go to Step 5 | |
5 |
Is the repair complete? | -- | Go to Step 18 | -- |
6 |
Is the repair complete? | -- | Go to Step 18 | -- |
7 |
Is the voltage reading less than the specified value? | 1 V | Go to Step 9 | Go to Step 8 |
8 | Repair a short-to-voltage condition in CKT 347. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 18 | -- |
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 | Go to Step 11 | Go to Step 10 |
10 | Repair a short-to-voltage condition in CKT 348. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 18 | -- |
11 |
Is the PASSENGER SENSELO more than the specified value? | 4.0 V | Go to Step 13 | Go to Step 12 |
12 |
Is the repair complete? | -- | Go to Step 18 | -- |
13 |
Is the voltage less than the specified value? | 1 V | Go to Step 15 | Go to Step 14 |
14 | Repair a short-to-voltage condition in CKT 1404. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 18 | -- |
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 | Go to Step 16 | |
16 | Repair a short-to-voltage condition in CKT 1403. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 18 | -- |
17 | An intermittent short-to-voltage condition caused DTC B1125 to set. Use the Diagnostic Aids for DTC B1125 and this table in order to find the intermittent short to voltage. Has the intermittent short to voltage been found and repaired? | -- | Go to Step 18 | -- |
18 |
Have all the SIR components been reconnected and properly mounted? | 4.0 V | -- | |
