Circuit Description
When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.
Upon passing these tests, the ignition and deployment loop voltages are measured to ensure that these voltages are within the normal ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deployment loops.
The SDM tests the wiring connection to extra devices, such as the side impact sensor, by letting an infinitesimal current flow through the internal circuit to verify the resistance. If the voltage is out of range, the SDM is unable to test the air bag system properly.
In the case of DTC B1103, test the battery and if necessary replace the battery with a new one. Erase the DTC using the scan tool.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B1449 Passenger Seat Occupant Classification Sensor Communication
Conditions for Running the DTC
Ignition voltage is within the normal operating voltage range.
Conditions for Setting the DTC
The Occupant Classification (OC) passenger system is defective or the air bag wiring harness is damaged.
Action Taken When the DTC Sets
The SDM commands the AIR BAG indicator ON.
Conditions for Clearing the DTC
Caution: The sensing and the diagnosis module (SDM) can maintain sufficient voltage to deploy the airbags and pretensioners for up to 1 minute after the ignition has been turned OFF and the fuse has been removed. If the airbags and pretensioners are not disconnected, do not begin service until one minute has been passed after disconnecting power to the SDM. Failure to do so may cause personal injury.
Caution: Do not strike or jolt the inflatable restraint sensing and diagnostic module (SDM). Before applying power to the SDM, make sure that it is securely fastened with the arrow facing toward the front of the vehicle. Failure to observe the correct installation procedure could cause SIR deployment, personal injury, or unnecessary SIR system repairs.
The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views | ||||
1 | Did you perform a Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Is the SDM charger discharged? | -- | Go to Step 3 | -- |
3 | Visually inspect for damage to the Occupant Classification (OC) sensor wiring. Is the OC sensor wiring damaged? | -- | Go to Step 4 | Go to Step 5 |
4 | Replace the air bag wiring. Did you complete the replacement? | -- | Go to Step 7 | -- |
5 | Test the resistance between the terminal 64 of the SDM and the terminal 2 of the OC sensor. Is the resistance approximately equal to the indicated value? | 0 ohms | Go to Step 6 | Go to Step 4 |
6 | Replace the OC sensor. Did you complete the replacement? | -- | Go to Step 7 | -- |
7 |
Does the DTC reset? | -- | Go to Step 8 | System OK |
8 | Verify the part numbers of the OC sensor and the SDM. Are the part numbers correct for the vehicle? | -- | Go to Step 2 | Go to Step 6 |
