Seat Belt Warning (Diagnostics): Overview Lexus RX III

SYSTEM DESCRIPTION

1. SEAT BELT WARNING SYSTEM DESCRIPTION Driver side seat belt warning light: When the driver side seat belt is not fastened with the engine switch on (IG), the driver side seat belt warning light on the combination meter assembly blinks. Front passenger side seat belt warning light: When the front passenger side seat belt is not fastened with the engine switch on (IG) and the front passenger side seat occupied, the front passenger side seat belt warning light on the radio receiver assembly*1 or accessory meter assembly*2 blinks. *1: w/ Navigation System *2: w/o Navigation System Seat belt warning buzzer: When the vehicle is driven at approximately 20 km/h (12 mph) while the driver side or front passenger side seat belt is unfastened, the seat belt warning buzzer in the combination meter assembly sounds at an interval of 1.2 seconds for 9.6 seconds*3 or 30 seconds*4. After that, the buzzer sounds at an interval of 0.4 seconds for 20 seconds*3 or 90 seconds*4. *3: w/ Occupant Classification System *4: w/o Occupant Classification System
2. FUNCTION OF MAIN COMPONENT Component Function Front seat inner belt assembly LH (Driver side seat belt buckle switch) Informs the center airbag sensor assembly of the driver side seat belt condition (fastened or unfastened). Front seat inner belt assembly RH (Front passenger side seat belt buckle switch) Informs the occupant classification ECU of the front passenger side seat belt condition (fastened or unfastened).*3 Informs the combination meter assembly of the front passenger side seat belt condition (fastened or unfastened).*4 Front occupant classification sensor LH/RH*3 Rear occupant classification sensor LH/RH*3 Informs the occupant classification ECU of the front passenger side seat condition (occupied or unoccupied). Occupant detection sensor (Separate type front seat cushion pad)*4 Informs the combination meter assembly of the front passenger side seat condition (occupied or unoccupied). Center airbag sensor assembly Sends the driver side, and front passenger side*3 seat belt buckle switch signals to the combination meter assembly via CAN communication. Occupant classification ECU*3 Sends the front passenger side seat belt buckle switch signal and occupant detection signal to the center airbag sensor assembly. *3: w/ Occupant Classification System *4: w/o Occupant Classification System

DESCRIPTION

When the engine switch is on (IG), the center airbag sensor assembly transmits front seat inner belt status signals to the combination meter assembly through CAN. If the driver side seat belt is not fastened, the combination meter assembly blinks the driver side seat belt warning light. If the seat belt is fastened, the warning light goes off.

Scheme 138

When the engine switch is on (IG), the center airbag sensor assembly transmits front seat inner belt status signals to the combination meter assembly through CAN. If the driver side seat belt is not fastened, the combination meter assembly blinks the driver side seat belt warning light. If the seat belt is fastened, the warning light goes off.

1. w/ Occupant Classification System The occupant classification ECU detects the state of the front seat inner belt assembly RH and occupant classification sensor when the front passenger side seat is occupied with the engine switch on (IG). If the front passenger side seat belt is not fastened, the front passenger side seat belt warning light on the accessory meter assembly*1 or radio receiver assembly*2 blinks. If the seat belt is fastened, the warning light goes off.
2. w/o Occupant Classification System When the front passenger side seat belt is not fastened with the engine switch on (IG) and the front passenger side seat occupied, the front passenger side seat belt warning light on the radio receiver assembly blinks. The occupant detection sensor detects if the front passenger side seat is occupied and sends signals to the combination meter assembly. The front seat inner belt assembly detects the front passenger side seat belt condition and sends signals to the combination meter assembly. After receiving the signals from the occupant detection sensor and front seat inner belt assembly, the combination meter illuminates the front passenger side seat belt warning light on the radio receiver assembly.

1. *1: w/ Navigation System
2. *2: w/o Navigation System

Scheme 139

Scheme 140

Scheme 141

1. w/ Occupant Classification System
2. w/o Occupant Classification System

1. w/ Occupant Classification System The occupant classification ECU detects the state of the front seat inner belt assembly RH and occupant classification sensor when the front passenger side seat is occupied with the engine switch on (IG). If the front passenger side seat belt is not fastened, the front passenger side seat belt warning light on the accessory meter assembly*1 or radio receiver assembly*2 blinks. If the seat belt is fastened, the warning light goes off.
2. w/o Occupant Classification System When the front passenger side seat belt is not fastened with the engine switch on (IG) and the front passenger side seat occupied, the front passenger side seat belt warning light on the radio receiver assembly blinks. The occupant detection sensor detects if the front passenger side seat is occupied and sends signals to the combination meter assembly. The front seat inner belt assembly detects the front passenger side seat belt condition and sends signals to the combination meter assembly. After receiving the signals from the occupant detection sensor and front seat inner belt assembly, the combination meter illuminates the front passenger side seat belt warning light on the radio receiver assembly.

1. *1: w/ Navigation System
2. *2: w/o Navigation System