DTC B1603: Seat belt pre-tensioner (driver's side) (squib) system (short circuit between squib circuit terminals): Notes
WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
If DTC B1603 is stored in the SRS-ECU, always diagnose the CAN main bus line.