Lexus RX300 (MCU15). Manual - part 114

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BODY ELECTRICAL

TROUBLESHOOTING

BE–3

LEXUS RX300   (RM785E)

Headlight does not come on.

1. Headlight Control Relay (Engine Room J/B)

2. Headlight Dimmer Switch

3. Light Control Switch

4. Body ECU

5. Wire Harness

6. Headlight Bulb

BE–31

BE–31

BE–31

DI–564

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–

Headlight does not come on with light control switch in HEAD.

1. Light Control Switch

2. Body ECU

3. Wire Harness

BE–31

DI–564

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Headlight does not go out with light control switch in OFF.

1. Headlight Control Relay (Engine Room J/B)

2. Wire Harness

BE–31

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Headlight is flicker.

1. Headlight Bulb

2. Wire Harness

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–

Headlight is dark.

1. Headlight Bulb

2. Wire Harness

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–

Taillight does not come on with light control switch in TAIL.

1. Taillight Control Relay (Instrument Panel J/B)

2. Light Control Switch

3. Wire Harness

BE–31

BE–31

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Taillight does not go out with light control switch in OFF.

1. Taillight Control Relay (Instrument Panel J/B)

2. Light Control Switch

3. Wire Harness

BE–31

BE–31

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Headlight do not come on with engine running and light control

switch in OFF.

1. ECU–B Fuse (Engine Room J/B)

2. GAUGE Fuse (Instrument Panel J/B)

3. DRL Fuse (Engine Room R/B No.3)

4. Daytime Running Light Relay

5. Daytime Running Light No.3 and No.4 Relay

6. Body ECU

7. Generator L Terminal

8. Parking Brake Switch

9. Brake Fluid Level Warning Switch

10.Wire Harness

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–

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BE–31

BE–31

DI–564

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BE–68

BE–68

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AUTOMATIC LIGHT CONTROL SYSTEM:

Symptom

Suspect Area

See page

”Automatic light control system” does not operate.

1. ECU–IG Fuse (Instrument Panel J/B)

2. DOME Fuse (Engine Room J/B)

3. Automatic Light Control Sensor

4. Light Control Switch

5. Door Courtesy Switch

6. Body ECU

7. Driver Door ECU

8. Wire Harness

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BE–31

BE–31

BE–48

DI–564

DI–598

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AUTO TURN OFF SYSTEM:

Symptom

Suspect Area

See page

Auto turn–off system does not operate when the driver’s door is

opened.

1. Drivers Door Courtesy Switch

2. Driver Door ECU

3. Multiplex Communication Circuit

4. Body ECU

BE–48

DI–598

DI–676

DI–564

Headlight and taillight does not come on.

1. Body ECU

2. Wire Harness

DI–564

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Headlight and taillight stays on.

1. Body ECU

2. Wire Harness

DI–564

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BE–4

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BODY ELECTRICAL

TROUBLESHOOTING

LEXUS RX300   (RM785E)

FOG LIGHT SYSTEM

Symptom

Suspect Area

See page

Fog light does not light up with light control SW HEAD

(Headlight is normal.)

1. FR FOG Fuse (Instrument Panel J/B)

2. Fog Light Relay (Instrument Panel J/B)

3. Fog Light Switch

4. Wire Harness

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BE–41

BE–31

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Fog light does not light up with light control SW HEAD

(Headlight does not light).

1.

*1

 Other Parts

2. Wire Harness

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Only one light does not light up.

1. Bulb

2. Wire Harness

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Rear fog light does not light with light control SW HEAD 

(Headlight is normal.)

1. Bulbs

2. FR FOG Fuse (Instrument Panel J/B)

3. Rear Fog Light Switch

4. Wire Harness

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BE–41

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Rear fog light does not light with light control SW HEAD 

(Headlight does not light.)

1. Inspect Headlight and Taillight System

2. Wire Harness

BE–31

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*1: Inspect Headlight System
TURN SIGNAL AND HAZARD WARNING SYSTEM

Symptom

Suspect Area

See page

”Hazard” and ”Turn” do not light up.

1. Hazard Warning Switch

2. Turn Signal Switch

3. Turn Signal Flasher

4. Wire Harness

BE–44

BE–31

BE–44

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The flashing frequency is abnormal.

1. Bulb

2. Turn Signal Switch

3. Wire Harness

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BE–31

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Hazard warning light does not light up.

(Turn is normal)

1. HAZARD Fuse (Engine Room J/B)

2. Wire Harness

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Hazard warning light does not light up in one direction.

1. Hazard Warning Switch

2. Wire Harness

BE–44

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*

1

 Turn signal does not light up.

1. Ignition Switch

2. GAUGE Fuse (Instrument Panel J/B)

3. Turn Signal Switch

4. Wire Harness

BE–26

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BE–31

–

*

2

 Turn signal does not light up.

1. GAUGE Fuse (Instrument Panel J/B)

2. Turn Signal Switch

3. Wire Harness

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BE–31

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Turn signal does not light up in one direction.

1. Turn Signal Switch

2. Wire Harness

BE–31

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Only one bulb does not light up.

1. Bulb

2. Wire Harness

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*

1

: Combination Meter, Wiper and Washer do not operate.

*

2

: Combination Meter, Wiper and Washer are normal.

ILLUMINATION LIGHT SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.

Symptom

Suspect Area

See page

Illumination light do not light.

(Taillight is normal)

1. PANEL Fuse (Instrument Panel J/B)

2. Rheostat Light Control

3. Wire Harness

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BE–68

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BODY ELECTRICAL

TROUBLESHOOTING

BE–5

LEXUS RX300   (RM785E)

Illumination light do not light.

(Taillight does not light)

1. Taillight Control Relay (Instrument Panel J/B)

2. Taillight System

3. Rheostat Light Control

4. Wire Harness

5. PANEL Fuse (Instrument Panel J/B)

BE–31

BE–31

BE–68

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–

Only one light does not light.

1. Bulb

2. Wire Harness

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INTERIOR LIGHT SYSTEM
This system uses the multiplex communication system, so check diagnosis system of the multiplex commu-
nication system before you proceed with troubleshooting.

Symptom

Suspect Area

See page

All the lights do not come ON.

1. DOME Fuse (Engine Room J/B)

2. Body ECU

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DI–564

The light does not come ON when the driver’s door is opened.

1. Driver’s Door Courtesy Switch

2. Driver Door ECU

3. Multiplex Communication Circuit

4. Body ECU

5. Wire Harness

BE–48

DI–598

DI–676

DI–564

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The light does not come ON when the passenger’s door is

opened.

1. Passenger’s Door Courtesy Switch

2. Front Passenger Door ECU

3. Multiplex Communication Circuit

4. Body ECU

5. Wire Harness

BE–48

DI–620

DI–676

DI–564

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The light does not come on when the rear–right door is opened.

1. Rear–Right Door Courtesy Switch

2. Body ECU

3. Wire Harness

BE–48

DI–564

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The light does not come on when the rear–left door is opened.

1. Rear–Left Door Courtesy Switch

2. Body ECU

3. Wire Harness

BE–48

DI–564

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Only one of the bulbs comes ON.

1. Bulb

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The illumination does not fade out when all the doors are closed.

1. Courtesy Switch

2. Driver Door ECU

3. Front Passenger Door ECU

4. Multiplex Communication Circuit

5. Body ECU

6. Wire Harness

BE–48

DI–598

DI–620

DI–676

DI–564

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The illumination does not fade out immediately when the ignition

switch is turned to ACC or ON within 15 seconds after all the

doors are closed.

1. Ignition Switch

2. RADIO NO.2 Fuse (Instrument Panel J/B)

3. GAUGE Fuse (Instrument Panel J/B)

4. Body ECU

5. Wire Harness

BE–26

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–

DI–564

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The illumination does not fade out immediately when all the doors

are locked within 15 seconds after they are closed.

1. Door Unlock Detection Switch

2. Driver Door ECU

3. Front Passenger Door ECU

4. Multiplex Communication Circuit

5. Body ECU

6. Wire Harness

BE–97

DI–598

DI–620

DI–676

DI–564

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Interior light does not light up.

(in front personal light)

1. Bulb

2. Front Personal Light

3. Wire Harness

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BE–48

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Front personal light does not light up.

1. Bulb

2. Front Personal Light

3. Wire Harness

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BE–48

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BE–6

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BODY ELECTRICAL

TROUBLESHOOTING

LEXUS RX300   (RM785E)

Rear personal light does not light up.

1. Bulb

2. Rear Personal Light

3. Wire Harness

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BE–48

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Vanity light does not light up.

1. Bulb

2. Vanity Light

3. Wire Harness

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BE–48

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Luggage compartment light does not light up.

1. Bulb

2. Luggage Compartment Door Courtesy Switch

3. Wire Harness

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BE–48

–

Courtesy light does not light up.

1. Bulb

2. Door Courtesy Switch

3. Wire Harness

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BE–48

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STOP LIGHT SYSTEM

Symptom

Suspect Area

See page

Stop light does not light up.

1. STOP Fuse (Instrument Panel J/B)

2. Stop Light Switch

3. Light Failure Sensor

4. Wire Harness

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BE–53

BE–53

–

Stop light always lights up.

1. Stop Light Switch

2. Wire Harness

BE–53

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Only one light always lights up.

1. Wire Harness

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Only one light does not light up.

1. Bulb

2. Wire Harness

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WIPER AND WASHER SYSTEM

Symptom

Suspect Area

See page

Wiper and washers do not operate.

1. WIPER Fuse (Instrument Panel J/B)

2. Wiper Switch

3. Wiper Motor

4. Body ECU

5. Wire Harness

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BE–56

BE–56

DI–564

–

Wipers do not operate in LO, HI or MIST.

1. Wiper Switch

2. Wiper Motor

3. Wire Harness

BE–56

BE–56

–

Wipers do not operate in INT.

1. Wiper Switch

2. Wiper Motor

3. Body ECU

4. Wire Harness

BE–56

BE–56

DI–564

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Washer motor does not operate.

1. Washer Switch

2. Washer Motor

3. Wire Harness

BE–56

BE–56

–

Wipers do not operate when washer switch in ON.

1. Washer Motor

2. Body ECU

3. Wire Harness

BE–56

DI–564

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Washer fluid does not operate.

1. Washer Hose and Nozzle

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D When wiper switch is at HI position, the wiper blade is in

contact with the body.

D When the wiper switch is OFF, the wiper blade does not

retract or the retract position wrong.

1. Wiper Motor *

2. Wire harness *

3. Body ECU

BE–56

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DI–564

*: Inspect wiper arm and blade set position.