During a side or frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the RH roof rail. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. A shorting bar used within the RH roof rail connector which will short together both RH roof rail high and low circuits when the connector is disconnected. This will help to prevent unwanted deployment of the inflator module during servicing.

Ignition voltage is between 9-16 volts.

The RH roof rail deployment loop resistance is less than 1.77 ohms.

The SDM commands the AIR BAG indicator ON.

Schematic Reference

SIR Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Important: When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.

•	The roof rail module

•	The SDM module

•	The SDM wiring harness connector

1. Ignition OFF, disconnect the RH roof rail in-line connector.
2. Disconnect the SDM connector. Refer to SDM replacement in Repair Instructions for connector location.
3. Test the high and low circuits between the SDM and RH roof rail for a short to ground or short between circuits. Verify that a short to ground or short between circuits does not exist.

⇒	If any of the above conditions are found make the appropriate repair.

4. If all circuits test normal then replace the SDM.
5. Ignition ON, use a scan tool to observe the SIR DTC display. Verify DTC B1478 is set current.

⇒	Replace the RH roof rail module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.