Lexus ES300 (1997 year). Manual - part 410

N22064

Theft Deterrent ECU

HEAD

8

J/C

D

7

Light Control Switch
(COMB. SW)

3

8

3

2

4

1

Headlight
Control Relay

40A MAIN

3

E/G Room J/B No.2

FL BLOCK

FL MAIN
3.0W

Battery

1

1

1

2

W–B

16

8

R–B

F

E

D

Headlights

T3

R–B

J11

R–B

R–B

R–B

J10

IJ1

J19

J18

J19

E

2K

2G

2B

J8

J6

B

B–G

R–B

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–417

569

1997 LEXUS ES300   (RM511U)

Headlight Control Relay Circuit

CIRCUIT DESCRIPTION

When the theft deterrent system is activated, it causes the Tr in the ECU to switch on and off at approximately
0.4 sec. intervals. This switches the headlight control relay on and off, thus flashing the headlights (See the
wiring diagram below).
In this condition, if any of the following operations is done, the Tr in the ECU goes off and the headlight control
relay switches off, thus stopping the headlights flashing:

(1)

Unlock the front LH or RH door with key.

(2)

Turn the ignition switch to ACC or ON position.

(3)

Unlock the doors with the wireless door lock control system.

(4)

Wait for approximately 60 seconds.

WIRING DIAGRAM

DI020–01

N20679

HEAD

(–)

(+)

DI–418

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

570

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

HINT:
The flow chart below is based on the premise that the headlights light up normally whenever the light control
switch is operated. If headlight operation is not normal when the light control switch is operated, proceed
to troubleshooting on page 

BE–2

.

1

Check voltage between terminal HEAD of theft deterrent ECU connector and
body ground.

PREPARATION:
Disconnect the theft deterrent ECU connector.
CHECK:
Measure voltage between terminal HEAD of theft deterrent
ECU connector and body ground.
OK:

Voltage: 10

∼

14V

NG

Check and repair harness and connector be-
tween theft deterrent ECU and headlight control
relay (See page 

IN–27

).

OK

Check and replace theft deterrent ECU.

N22065

Theft Deterrent ECU

TAIL

7

B

B

J/C

J34

10

C

C

J2
J/C

6

2

3

1

5

8

9

4

Instrument Panel J/B

1

1

FL MAIN
3.0W

Battery

Light Failure
Sensor

T3

G–R

G–R

G–R

G–R

B–R

B–G

IG1

1C

1B

1S

1C

10A TAIL

Taillight Control
Relay

FL BLOCK

Front Parking
Lights

F6

F11

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–419

571

1997 LEXUS ES300   (RM511U)

Taillight Control Relay Circuit

CIRCUIT DESCRIPTION

When the theft deterrent system is activated, it causes the Tr in the ECU to switch on and off at approximately
0.4 sec. intervals. This switches the taillight control relay on and off, thus flashing the taillights (See the wiring
diagram below).
In this condition, if any of the following operations is done, the Tr in the ECU goes off and the taillight control
relay switches off, thus stopping the taillights flashing:

(1)

Unlock the front LH or RH door with key.

(2)

Turn the ignition switch to ACC or ON position.

(3)

Unlock the doors with the wireless door lock control system.

(4)

Wait for approximately 60 seconds.

WIRING DIAGRAM

DI021–01

N20680

TAIL

(–)

(+)

DI–420

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

572

1997 LEXUS ES300   (RM511U)

INSPECTION PROCEDURE

HINT:
The flow chart below is based on the premise that the taillights light up normally whenever the light control
switch is operated. If taillight operation is not normal when the light control switch is operated, proceed to
troubleshooting on page 

BE–2

.

1

Check voltage between terminal TAIL of theft deterrent ECU connector and body
ground.

PREPARATION:
Disconnect the theft deterrent ECU connector.
CHECK:
Measure voltage between terminal TAIL of theft deterrent ECU
connector and body ground.
OK:

Voltage: 10

∼

14V

NG

Check and repair harness and connector be-
tween theft deterrent ECU and taillight control
relay (See page 

IN–27

).

OK

Check and replace theft deterrent ECU.