Lexus RX300 (MCU15). Service manual — part 124

I19134

Engine Room J/B
D HAZARD Fuse

Hazard Warning Switch

Combination Switch

Turn Signal Light

Instrument Panel J/B
D Turn Signal Flasher
D GAUGE Fuse

Turn Signal Light

BE053–05

–

BODY ELECTRICAL

TURN SIGNAL AND HAZARD WARNING SYSTEM

BE–43

LEXUS RX300 (RM785E)

TURN SIGNAL AND HAZARD WARNING SYSTEM

LOCATION

BE0UD–02

I19119

Right

Left

3

2

1

N21563

Wire Harness Side

1

2 3 4 5

6

7 8

9 10 11

13

12

14 15 16 17

BE–44

–

BODY ELECTRICAL

TURN SIGNAL AND HAZARD WARNING SYSTEM

LEXUS RX300 (RM785E)

INSPECTION

1.

INSPECT TURN SIGNAL SWITCH CONTINUITY

Switch position

Tester connection

Specified condition

Left turn

1 – 2

Continuity

Neutral

–

No continuity

Right turn

2 – 3

Continuity

If continuity is not as specified, replace the switch.

2.

INSPECT COMBINATION SWITCH CIRCUIT

Connect the wire harness side connector to the combination
switch and inspect wire harness side connector from the back
side.

Tester connection

Condition

Specified condition

1 – Ground

Constant

*Continuity

3 – Ground

Constant

*Continuity

2 – Ground

Ignition switch ON and turn signal switch position

Neutral

No voltage

2 – Ground

Hazard warning switch ON

Battery voltage

2 – Ground

Ignition switch ON and turn signal switch position

Left or Right

Battery voltage

*There is resistance because this circuit is grounded through
the bulb.
If the circuit is not as specified, inspect the circuit connected to
other parts.

I04474

RH LH

x2

x2

(21W)
Turn Signal Light Bulb

I04475

RH LH

x2

x2

(21W)
Turn Signal Light Bulb

I04046

Wire Harness Side

–

BODY ELECTRICAL

TURN SIGNAL AND HAZARD WARNING SYSTEM

BE–45

LEXUS RX300 (RM785E)

3.

INSPECT TURN SIGNAL FLASHER OPERATION

(a)

Connect the positive (+) lead from the battery to terminals
1 and 4, and the negative (–) lead to terminal 7.

(b)

Connect 2 turn signal bulbs to terminal 2 and 3 each and
connector the other side of them to negative (–) battery
terminal.

(c)

Check that the LH bulbs flushes when terminal 5 is con-
nected to the negative (–) battery terminal.

(d)

Check that the RH bulbs flushes when terminal 6 is con-
nected to the negative (–) battery terminal.

(e)

Disconnect the terminal 1 from the positive (+) battery ter-
minal.

(f)

Check that LH and RH bulbs flush when terminal 8 is con-
nected to the negative (–) battery terminal.

4.

INSPECT TURN SIGNAL FLASHER CIRCUIT

Disconnect the connector from the combination switch and in-
spect the connector on the wire harness side, as shown.

Tester connection

Condition

Specified condition

2 – Ground

Constant

Continuity

3 – Ground

Constant

Continuity

5 – Ground

Turn signal switch RIGHT or OFF

No continuity

5 – Ground

Turn signal switch LEFT

Continuity

6 – Ground

Turn signal switch LEFT or OFF

No continuity

6 – Ground

Turn signal switch RIGHT

Continuity

7 – Ground

Constant

Continuity

8 – Ground

Hazard warning switch OFF

No continuity

8 – Ground

Hazard warning switch ON

Continuity

1 – Ground

Ignition switch LOCK or ACC

No voltage

1 – Ground

Ignition switch ON

Battery voltage

4 – Ground

Constant

Battery voltage

If circuit is as specified, replace the relay.
If circuit is not as specified, inspect the circuits connected to oth-
er parts.

I04499

e–10–2

N21579

e–10–1

1 2

3 4

5 6 7 8 9 10

Wire Harness Side

BE–46

–

BODY ELECTRICAL

TURN SIGNAL AND HAZARD WARNING SYSTEM

LEXUS RX300 (RM785E)

5.

INSPECT HAZARD WARNING SWITCH CONTINUITY

Switch position

Tester connection

Specified condition

Switch OFF

5 – 6

No continuity

Switch ON

5 – 6

Continuity

Illumination circuit

8 – 9

Continuity

If continuity is not as specified, replace the switch.

6.

INSPECT HAZARD WARNING SWITCH CIRCUIT

Disconnect the switch connector and inspect the connection on
the wire harness side.

Tester connection

Condition

Specified condition

*

1

8 – Ground

Light control switch position OFF

No voltage

*

1

8 – Ground

Light control switch position TAIL or HEAD

Battery positive voltage

*

1

: Illumination

*

2

: There is resistance because this circuit is grounded through

the bulb.
If the circuit is not as specified, inspect the circuits connected
to other parts.