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 or B1104, 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 B1104 Passenger Seat Occupant Classification System (OCS) Voltage Out of Range
Conditions for Running the DTC
Ignition voltage is within the normal operating voltage range.
Conditions for Setting the DTC
The voltage supplied from the battery remains less than 10.6 volts for 16 seconds.
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 | Measure the voltage terminal 1 of occupant classification system (OCS) sensor connector. Does the voltage measure greater than specified? | 10.6 V | Go to Step 8 | Go to Step 3 |
3 | Check fuse F11. Is the fuse blown? | -- | Go to Step 7 | Go to Step 5 |
4 | Replace fuse F11. Did you complete the replacement? | -- | Go to Step 9 | -- |
5 | Measure voltage at fuse F11. Does the voltage measure greater than specified? | 10.6 V | Go to Step 6 | Go to Step 8 |
6 | Test OCS ignition voltage circuit for an open or high resistance. Did you find and correct the condition? | -- | Go to Step 9 | -- |
7 | Test OCS ignition voltage circuit for a short to ground. Did you find and correct the condition? | -- | Go to Step 4 | -- |
8 | Repair voltage supply circuit to fuse F11. Did you complete the repair? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
