Front Passenger Side Seat Belt Warning Light Malfunction [08/2013 - ]: Description

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.

w/ Occupant Classification System
When the power switch is turned on (IG), the occupant detection ECU sends a signal to the airbag sensor assembly to indicate the state of the front seat inner belt assembly RH and also whether the front passenger seat is occupied. The airbag sensor assembly sends those signals to the combination meter assembly via CAN communication. The combination meter assembly illuminates, blinks or turns off the seat belt warning light on the combination meter assembly in accordance with these signals.
w/o Occupant Classification System
The occupant detection sensor (separate type front seat cushion pad) detects if the passenger seat is occupied and sends signals to the combination meter assembly. The front seat inner belt assembly RH detects the front passenger seat belt condition and sends signals to the combination meter assembly. After receiving the signals from the occupant detection sensor (separate type front seat cushion pad) and front seat inner belt assembly RH, the seat belt warning light on the combination meter assembly will blink or go off.

HINT:

The seat belt warning light on the combination meter assembly is used for both the driver seat and front passenger seat.