DTC B1C43-23: Master Interior Light Switch - Signal stuck low: Action

NOTE: This DTC may be induced by the driver operating the interior lamp switch for longer than 60 seconds.

Refer to the appropriate system wiring diagrams and check the interior lamp switch signal circuit for short circuit to ground. Repair the wiring harness or install a new interior lamp as necessary
Check the operation of the interior lamp switch. Install a new interior lamp as necessary