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.

This diagnostic procedure supports the following DTC:

DTC B1440 Passenger Seat Occupant Classification System (OCS) Circuit Short to Ground

Ignition voltage is within the normal operating voltage range.

The OC sensor wiring is shorted to ground.

The SDM commands the AIR BAG indicator ON.

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

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.