Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: System Description

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Interior / Seat Belt / Seat Belt Warning System(for Gasoline Model) / System Description

SYSTEM DESCRIPTION

SEAT BELT WARNING SYSTEM DESCRIPTION

(a) Seat belt warning light operation for driver seat belt:

The seat belt warning light on the combination meter assembly illuminates, blinks or turns off in accordance with the driver seat belt state, vehicle speed, shift lever position and parking brake state.

(b) Seat belt warning light operation for front passenger seat belt:

The seat belt warning light on the combination meter assembly illuminates, blinks or turns off in accordance with whether the front passenger seat is occupied, the front passenger seat belt state, vehicle speed, shift lever position and parking brake state.

(c) Rear seat belt warning light:

The rear seat belt warning light on the radio and display receiver assembly illuminates, blinks or turns off in accordance with the rear door state, vehicle speed and rear seat belt state.

(d) Front seat belt warning buzzer:

After turning the engine switch on (IG), if the driver seat belt is not fastened within 1.8 seconds, the seat belt warning buzzer in the combination meter assembly will sound at an interval of 1.2 seconds for 6 seconds.

When the vehicle is driven at approximately 20 km/h (12 mph) or more with the front passenger seat occupied and the driver or front passenger seat belt not fastened, the seat belt warning buzzer in the combination meter assembly will sound once.

When 24 seconds have passed after the buzzer sounded, the seat belt warning buzzer in the combination meter assembly will sound at an interval of 1.2 seconds for 6 seconds.

After that, the seat belt warning buzzer in the combination meter assembly will sound at an interval of 0.4 seconds for 90 seconds.

(e) Rear seat belt warning buzzer:

When the vehicle is driven at approximately 20 km/h (12 mph) or more with a rear seat belt not fastened, the seat belt warning buzzer in the combination meter assembly will sound at an interval of 1.2 seconds for 6 seconds.

After that, the seat belt warning buzzer in the combination meter assembly will sound at an interval of 0.4 seconds for 30 seconds.

FUNCTION OF MAIN COMPONENTS

Component

Function

Front seat inner belt assembly LH

Informs the airbag ECU assembly of the driver seat belt condition (fastened or unfastened).

Front seat inner belt assembly RH

Informs the occupant detection ECU of the front passenger seat belt condition (fastened or unfastened).
  • Front occupant classification sensor LH
  • Rear occupant classification sensor LH

Informs the occupant detection ECU of the front passenger seat condition (occupied or unoccupied).

Combination meter assembly
  • Illuminates, blinks or turns off the seat belt warning light.
  • Sounds the seat belt warning buzzer.

Occupant detection ECU

Sends the front passenger seat belt buckle switch signal and occupant detection signal to the airbag ECU assembly via CAN communication.

Airbag ECU assembly
  • Sends the driver seat belt buckle switch signal to the main body ECU (multiplex network body ECU) via CAN communication.
  • Sends the front passenger seat belt buckle switch signal to the combination meter assembly via CAN communication.

Radio and display receiver assembly

Illuminates, blinks or turns off the rear seat belt warning light.
  • Rear seat inner belt assembly LH
  • Rear seat inner with center belt assembly RH

Informs the combination meter assembly of each rear seat belt condition (fastened or unfastened).

Rear door courtesy light switch assembly (LH/RH)

Informs the main body ECU (multiplex network body ECU) of the rear door condition (open or closed).

Main body ECU (multiplex network body ECU)

Sends the driver seat belt buckle switch signal, parking brake signal and rear door courtesy light switch signal to the combination meter assembly via CAN communication.

Skid control ECU (brake actuator assembly)

Sends the vehicle speed signal to the combination meter assembly via CAN communication.

ECM

Sends the shift position signal to the combination meter assembly via CAN communication.
    Rear Seat Belt Warning Light Malfunction

    System Diagram

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