Lexus SC300 / Lexus SC400. Manual - part 224

TROUBLESHOOTING

You will find the cause of trouble more easily by properly using the table shown below. In this table, the num-
bers indicate the order priority of causes of trouble. Check each part in the order shown. If necessary, re-
place the parts.

See page

B–4,21

BE–26

BE–4

,20

BE–91

BE–90

BE–92

BE–91

BE–93

–

Trouble

Part Name

AM1 Fuse

Ignition Switch

WIPER Fuse

Wiper Switch

Wiper Motor

W

asher Motor

W

asher Switch

W

asher Hose and Nozzle

Wire Harness

Wipers and washers do not operate.*

1

1

3

2

4

5

6

Wipers and washers do not operate.*

2

2

1

3

4

5

Wipers and washers do not operate.*

3

1

2

3

4

Wipers do not operate in LO, HI or MIST.

1

2

3

Wipers do not operate in INT.

1

2

3

Washer motor does not operate.

2

1

3

Wipers do not operate when washer switch
is ON.

1

2

Washer fluid does not spray.

1

*

1

:  Door Lock and Power Windows do not operate

*

2

:  Door Lock and Power Window are normal. Combination Meter and Turn Signal do not operate.

*

3

:  Combination Meter and Turn Signal are normal.

BE–94

–

BODY ELECTRICAL SYSTEM

Wiper and Washer System

COMBINATION METER

–

BODY ELECTRICAL SYSTEM

Combination Meter

BE–95

DESCRIPTION

The combination meter has various meters and gauges which show the vehicle’s condition, warning lights which
monitor abnormalities in the vehicle and inform the driver, indicator lights which inform the driver of the condition
of each part of vehicle, and a function for illumination and brightness adjustment of meters and gauges.
The component parts of this system and their functions are described in the following table.

Parts Name

Function

Speedometer

The speedometer needle moves in accordance with signals from the speed sensor to
indicate the vehicle’s speed.

Tachometer

The tachometer needle moves in accordance with signals from the igniter to indicate the
engine’s speed.

Water Temperatrue
Gauge

The water temperature gauge’s needle moves in accordance with signals from the send-
er gauge and indicates the temperature of the engine coolant.

Fuel Gauge

The fuel gauge needle moves in accordance with signals from the sender gauge, indicat-
ing the amount of fuel remaining in the fuel tank.

Odometer

The odometer counts the total distance traveled by the vehicle in accordance with pulse
signals from the speed sensor.

Twin Trip Switch

The twin trip meter counts the distance traveled by the vehicle in accordance with pulse
signals from the speed sensor. It can be reset using a switch and can be used to switch
between trip meters A and B.

Circuit Plate

This plate contains the circuitry for each meter and gauge and for each warning light and
indicator light, as well as an internal engine oil level warning drive circuit, drive circuits for
the odometer and trip meter and brightness adjustment circuitry for each indicator.

Speed Sensor

Mounted in the transmission, this sensor outputs pulse signals to the combination meter
in accordance with the speed of the output shaft.

Twin Trip Switch

Operation of this switch switches between the A and B trip meters and sends reset sig-
nals to the combination meter.

Water
Temperature Sender
Gauge

This sender converts engine coolant temperatures to a resistance value in signal form to
the combination meter.

Fuel Sender Gauge

This sender converts the level of fuel remaining in fuel tank to resistance value and
sends the resistance value in signal form to combination meter.

Rheostat Light
Control Volume

In order to adjust the degree of illumination of the combination meter, the resistance val-
ue of the built–in variable resistor is sent to the combination meter and rheostat light
control.

Fuel Level Warning
Switch

When the level of fuel remaining falls below a predetermined level, continuity is estab-
lished with this switch, which is built into the fuel sender gauge, causing a warning light
to light up.

Low Oil Pressure
Warning Switch

This switch is mounted on the engine block. Continuity is established in this switch when
the oil pressure is low, causing a warning light to light up.

Integration Relay (Seat
Belt Warning Relay)

This relay receives current from fuse GAUGE and DOME and is connected to each
buckle switch, door courtesy switch, key unlock warning switch and warning light. As
part of the seat belt warning system, it sounds a chime and lights a warning light when
seat belts are unfastened. As part of the key unlock warning system, it sounds a chime
when the set conditions are fulfilled.

Light Failure Sensor

This sensor senses when a bulb in rear combination light is burnt out and lights up a
warning light.

BE–96

–

BODY ELECTRICAL SYSTEM

Combination Meter

Parts Name

Function

Coolant Level
Warning Switch

This switch is installed in the radiator reservoir tank. It lights up a warning light when the
coolant level becomes low.

Engine Oil Level
Warning Switch

This switch is mounted in the engine oil pan. It lights a warning light when the engine oil
level is low.

Brake Fluid Level
Warning Switch

This switch is mounted in the brake master cylinder reservoir tank. It lights up a warning
light when the brake fluid level is low.

Parking Brake Switch

This switch is on the parking brake lever bracket. Continuity in this switch is established
when the lever is released, causing a warning light to light up.

Door Courtesy Switch

Continuity is established in this switch when a door is opened, causing a warning light to
light up.

Warning Lights

When an abnormality is detected in the vehicle, current is sent to these lights, or they are
grounded, causing them to light up.

Indicator Lights

Current is sent to these lights, or they are grounded, causing them to light up and indicate
the vehicle’s condition to the driver.

Window Washer Level
Warning Switch

This switch is mounted in the window washer tank. It lights a warning light when the
window washer level becomes low.

–

BODY ELECTRICAL SYSTEM

Cominbation Meter

BE–97