Lexus SC300 / Lexus SC400. Manual - part 206

IGNITION SWITCH

Description

The ignition switch is supplied with power from the battery via a fusible link. Power is supplied to each fuse
and relay according to the position of the switch, whether “CC” ‘‘ON” or “START”. The key unlock warning
switch, which detects the set condition of the key, is built into this switch.

Parts Location

Wiring and Connector Diagrams

–

BODY ELECTRICAL SYSTEM

Ignition Switch

BE–25

Parts Inspection
(Ignition Switch and Key Unlock
Warning Switch)

REMOVAL AND INSTALLATION OF
IGNITION SWITCH AND KEY UNLOCK
WARNING SWITCH

1. DISCONNECT 

BATTERY 

TERMINALS

CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and negative (–) terminal
cable is disconnected from the battery.

2. 

REMOVE FOLLOWING PARTS:
(See page 

BO–112

)

•

No. 1 under cover

•

No. 1 lower finish panel

•

Console box assembly

•

Instrument panel lower center

3. 

REMOVE IGNITION SWITCH
(a) Disconnect 

connector.

(b)  Remove three screws and the switch from the key

cylinder and wire harness clamp.

4. 

INSTALL IGNITION SWITCH
For installation, follow the removal procedure in reverse.

INSPECTION OF IGNITION SWITCH AND
KEY UNLOCK WARNING SWITCH

1. 

INSPECT IGNITION SWITCH
(Switch continuity)
Inspect the switch continuity between terminals.

Terminal

Switch position

LOCK

ACC

ON

START

If continuity is not as specified, replace the switch.

BE–26

–

BODY ELECTRICAL SYSTEM

Ignition Switch

(Switch circuit)
Connect the switch connector and inspect the connector on
the wire harness side from the back side as shown.

Check for

Tester connection

Condition

Specified value

Voltage

2–Ground

Ignition switch turned to ON

Battery voltage

3–Ground

Ignition switch turned to ACC or ON

4–Ground

Constant

5–Ground

Ignition switch turned to START

6–Ground

Ignition switch turned to ON

11–Ground

Constant

If circuit is not as specified, inspect the switch or refer to

BE–25

 wiring diagram and inspect the circuits connected to

other parts.

2. 

INSPECT KEY UNLOCK WARNING SWITCH
(Switch continuity)
Inspect the switch continuity between terminals.

Terminal

Switch position

ON

OFF

(Ignition Key removed)

(Ignition Key set)

If continuity is not as specified, replace the switch.

(Switch circuit)
Connect the switch connector and inspect the connector on
the wire harness side from the back side as shown.

Check for

Check connection

Condition

Specified value

Continuity

10–Ground

Ignition key removed

No continuity

Ignition key set

Continuity

9–Ground

Constant

Continuity

If circuit is not as specified, inspect the switch or wire harness.

–

BODY ELECTRICAL SYSTEM

Ignition Switch

BE–27

LIGHTING SYSTEM

BE–28

–

BODY ELECTRICAL SYSTEM

Lighting System