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.

At this time, the SDM will establish communication with the passenger presence detection (PPD)/seat belt reminder (SBR) and the PPD/SBR will respond to the SDM by commanding the passenger air bag OFF indicator On for five seconds.

The SDM monitors the PPD/SBR status (occupied, not occupied, seated, defect) cyclically. These 4 messages should transmit every 1.2 seconds to the SDM.

Ignition voltage is within the normal operating voltage range.

A communication error occurs between the SDM and the PPD sensor.

The SDM commands ON the AIR BAG warning lamp.

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

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 I/P module

•	The SDM module

•	The I/P wiring harness connector

•	The SDM wiring harness connector

1. Ignition OFF, replace the PPD sensor.
2. Use the scan tool to clear the DTCs.
3. Operate the vehicle within the Conditions for Running the DTC as specified in the text.

⇒	If DTC B1407 set again, replace the SDM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for SDM replacement, setup, and programming