Lexus RX300 (MCU15). Service manual - part 61

BE

BODY ELECTRICAL — LIGHTING

117

JDAYTIME RUNNING LIGHT SYSTEM

This system is designed to automatically activate the low-beam of the headlights during the daytime to
keep the car highly visible to other vehicles. This system is optional equipment on certain models for LHD
vehicle. This system is controlled by the body ECU. This system is enabled when the conditions given
below are met.

D Ignition switch ON condition

D Alternator L terminal signal input

D Light control switch OFF condition

" Wireling Diagram A

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Battery

TAIL

IG

TRLY

Taillight
Relay

Headlight
Relay

Body
ECU

HRLY To Taillight

Dimmer
Relay

Engine
ECU

BEAN

Alternator

HI

LO

HI

LO

JHEADLIGHT BEAM LEVEL

This system keeps the low-beam of the headlights adjusted to the appropriate level in accordance with
the number (weight) of passengers and volume of luggage.
The headlight low-beam level can be adjusted by operating the headlight beam level control switch.

187BE03

0

5

Headlight Beam Level Control Switch

LHD Model

BODY ELECTRICAL — LIGHTING

118

JAUTOMATIC LIGHT CONTROL SYSTEM

D An automatic light control system, which automatically turns the headlights and taillights ON and OFF

according to the brightness of the vehicle’s surroundings, has been adopted.

D Based on the signals output by the automatic light control sensor located on the instrument panel, the

body ECU detects the brightness of the surroundings to control operation of the headlights and taillights.

JLIGHT AUTO TURN-OFF SYSTEM

D When the ignition key is turned from ON to LOCK position and the driver’s door is opened with the

taillights and headlights on, this system automatically turns them off.

D This system is controlled by the body ECU.

JILLUMINATED ENTRY SYSTEM

D When a door is unlocked through a key operation or transmitter operation, or if a door is opened or

closed, the illuminated entry system turns ON the dome light and the ignition key illumination.

D If the ignition switch is turned to the ACC or ON position or if all doors are locked during the 15 seconds

in which these lights are ON, they will immediately turn OFF.

D This system is controlled by the body ECU.

JLIGHT REMINDER SYSTEM

When the ignition key is turned from the ON or ACC to LOCK position while the driver’s door open with
the taillights or headlights turned on, this system warns the driver that the lights remain on by sounding
the buzzer.

BE

BODY ELECTRICAL — METER

119

METER

JCOMBINATION METER

1. General

D An optitron display type combination meter has been adopted. The optitron display type meter realizes

excellent visibility through the use of smoke acrylic in the protective panel, and a cold cathode lamp
that is vary bright and has high contrast for illuminating the indicator and the dial (see-through illumina-
tion). Its face is black when no current is applied.

D An odometer and trip meter which used LCD (Liquid Crystal Display) have been adopted.

D An air conditioner and combination meter integrated ECU is enclosed in the combination meter. This

ECU comprises a meter ECU that computes and processes the signals that are input and output from
the various systems in the vehicle to the combination meter, and an air conditioner ECU that controls
the temperature of the air conditioner. This ECU maintains communication with other ECUs through
the BEAN (Body Electronics Area Network).

D The speedometer electrically detects the signals from the vehicle speed sensor (for ABS) via the ABS

ECU.

D The fuel gauge operates in accordance with the data that has been corrected by the air conditioner and

combination meter integrated ECU. This prevents the fluctuation of the indicator and ensures a more
accurate display of the remaining fuel volume.

187BE04

LHD Model

LCD

LCD

RHD Model

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BODY ELECTRICAL — METER

120

2. Fuel Gauge

The fuel gauge is operated by the air conditioner and combination meter integrated ECU. The air conditioner
and combination meter integrated ECU receives the inputs of the fuel sender gauge signal and the fuel
injection time signal (correction data) from the engine ECU via the BEAN.
The air conditioner and combination meter integrated ECU computes and corrects these two signals to
prevent the fluctuation of the indicator and to ensure a more accurate display of the remaining fuel volume.
However, if a fuel injection time signal from the engine ECU is not input from the BEAN, only the correction
function will be disabled in the air conditioner and combination meter integrated ECU. Therefore, the fuel
gauge will display the remaining fuel volume in a normal manner in accordance with the signal received
from the fuel sender gauge.

" System Diagram A

187BE06

Fuel Sender

Gauge

Combination Meter

A/C and Combination 
Meter Integrated ECU 

enclosed

BEAN

Engine ECU

Fuel

Injection

Time Signal