Lexus ES300 (1997 year). Service manual - part 411

N22066

Theft Deterrent ECU

ACC

13

12

IG

P–L

A

A

J/C

J7

P–L

B–R

B

C

B–R

Instrument Panel J/B

1

6

8

1

1

2

3

L–R

4

B–Y

AM1

2

Ignition Switch

W

B–R

B–R

1

FL BLOCK

1

B–G

FL MAIN
3.0W

Battery

J/C

F6

100A ALT

F11

1K

1K

1K

1T

1B

1D

40A AM1

15A ECU–IG

15A CIG

T4

T4

J6

J5

ACC

IG1

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–421

573

1997 LEXUS ES300   (RM511U)

Ignition Switch Circuit

CIRCUIT DESCRIPTION

When the ignition switch is turned to the ACC position, battery positive voltage is applied to the terminal ACC
of the ECU. Also, if the ignition switch is turned to the ON position, battery positive voltage is applied to the
terminals ACC and IG of the ECU. When the battery positive voltage is applied to the terminal ACC of the
ECU while the theft deterrent system is activated, the warning stops. Furthermore, power supplied from the
terminals ACC and IG of the ECU is used as power for the door courtesy switch, and position switch, etc.

WIRING DIAGRAM

DI022–01

N20675

Instrument Panel J/B

ECU–IG Fuse

CIG Fuse

AB0119

N20681

I01283

ON

ACC

IG

(+)

(–)

DI–422

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

574

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

1

Check CIG and ECU–IG fuses.

PREPARATION:
(a)

Remove the fuse box opening cover.

(b)

Remove CIG and ECU–IG fuses from instrument panel
junction block.

CHECK:
Check continuity of CIG and ECU–IG fuses.
OK:

Continuity

NG

Check for short in all the harness and compo-
nents connected to the CIG and ECU–IG fuses
(See attached wiring diagram).

OK

2

Check voltage between terminals IG and ACC of theft deterrent ECU and body
ground.

PREPARATION:
(a)

Disconnect the theft deterrent ECU connectors.

(b)

Turn ignition switch ON.

CHECK:
Measure voltage between terminals IG and ACC of theft deter-
rent ECU connector and body ground.
OK:

Voltage: 10

∼

14V

NG

Check and repair harness and connector be-
tween theft deterrent ECU and battery
(See page 

IN–27

).

OK

Check and replace theft deterrent ECU.

N22067

1D

II

L–B

W–B

J/C

T4

Instrument Panel J/B

Theft Deterrent ECU

KSW

J10

Key Unlock
Warning Switch

1M

Instrument Panel J/B

2

1

5

3

7

7

A

1M

1D

B

B

L–B

L–B

15

W–B

SR4924

N14675

I00634

2 (–)

1 (+)

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–423

575

1997 LEXUS ES300   (RM511U)

Key Unlock Warning Switch Circuit

CIRCUIT DESCRIPTION

The key unlock warning switch goes on when the ignition key is inserted in the key cylinder and goes off when
the ignition key is removed.
The ECU operates the key confinement prevention function while the key unlock warning switch is on.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check key unlock warning switch.

PREPARATION:
Disconnect key unlock warning switch connector.
CHECK:
Check continuity between terminal 1 and 2 of key unlock warn-
ing switch connector, when the key is inserted to the key cylin-
der or removed.
OK:

Switch position

Tester connection

Specified condition

ON (Key inserted)

1 – 2

Continuity

OFF (Key removed)

–

No continuity

NG

Replace key unlock warning switch.

DI023–01

DI–424

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

576

1997 LEXUS ES300   (RM511U)

OK

2

Check harness and connectors between ECU and key unlock warning switch,
key unlock warning switch and body ground (See page 

IN–27

).

NG

Repair or replace harness or connector.

OK

Check and replace theft deterrent ECU.*1

*1: When there is a malfunction that the theft deterrent system
cannot be set, proceed to the next numbered circuit inspection
shown on matrix chart (See page 

DI–405

).