Lexus RX300 (MCU15). Service manual — part 308

DI–464

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DIAGNOSTICS

THEFT DETERRENT SYSTEM

LEXUS RX300 (RM785E)

INSPECTION PROCEDURE

HINT:
In case of using the hand–held tester, start the inspection from step 1 and in case of not using the hand–held
tester, start from step 2.

1

Check luggage compartment door lock and unlock switch using hand–held tes-
ter.

PREPARATION:
Connect the hand–held tester to the DLC 3.
CHECK:
Check the luggage compartment door lock and unlock switch using DATA LIST.

OK

Proceed to next circuit inspection shown in
problem symptoms table (See page DI–452).

NG

2

Check back door key lock and unlock switch (See page BE–97).

NG

Repair or replace back door key lock and unlock
switch.

OK

3

Check harness and connector between theft deterrent ECU and key lock and un-
lock switch, key lock and unlock switch and body ground (See page IN–32).

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 in problem symptom table (See page DI–452).

I19247

Theft Deterrent ECU

CLTS

9

L–B

4

T15
Theft Deterrent Siren

W–B

T5

A

J15
J/C

IM2

BM

TRIG

10

T5

+B1

11

T4

CONT

4

TRIG

GND

+B

Instrument Panel J/B

To
ECU–B Fuse

*1: LHD
*2: RHD

Y

G–B (*1)

W–L (*2)

(*1)

L–B

2

3

12

IM2

Y

6

1H

9

1D

10

1G

G–B (*1)

W–L (*2)

7

IM1

7

IM2

(*2)

1

G–B (*1)

W–L

(*2)

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DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–465

LEXUS RX300 (RM785E)

Self Power Siren

CIRCUIT DESCRIPTION

Based on the alarm sounding state input from the theft deterrent ECU (to the TRIG terminal) an alarm is
issued.
However, the armed/disarmed state is determined by the CONT terminal, which monitors vehicle status, and
input to the TRIG terminal is only accepted from the ECU while armed state is ON.
Moreover, open circuit detection is only carried out while armed state is ON.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:
In case of using the hand–held tester, start the inspection from step 1 and in case of not using the hand–held
tester, start from step 2.

1

Check self power siren using hand–held tester.

PREPARATION:
Connect the hand–held tester to the DLC 3.
CHECK:
Check that the self power alarm can operated in an ACTIVE TEST.
OK:
The self power alarm should sound.

OK

Proceed to next circuit inspection shown in
problem symptoms table (See page DI–452).

DI61I–02

I19173

1

2

4

3

*1: wave pattern

*2: wave pattern

HIGH
(1.5 V or more)

HIGH
(1.5 V or more)

LOW
(Below 1.5 V)

LOW
(Below 1.5 V)

T1: 0.15 – 1.3 secs
T2: 0.15 – 0.25 secs

T1

T1

T1

T2

DI–466

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

LEXUS RX300 (RM785E)

NG

2

Check self power siren.

PREPARATION:
Remove the self power siren.
CHECK:
(a)

Case 1:
Check terminal 3 in case of the system set signal is not
input to the siren.

(b)

Case 2:
Check terminal 4 in case of the siren drive signal is not in-
put when the alarm is triggered.

OK:

Tester connection

Condition

Specified condition

1 – Ground

Constant

Battery voltage

4 – Ground

Constant

No voltage

When transforming from

armed or arming prepara-

tion state to disarmed

state.

Using an oscilloscope *1

2 – Ground

When transforming from

the arming preparation

state to armed state.

Using an oscilloscope *2

Normal condition

Approx. 1.4 V

3

Ground

Normal condition

Battery voltage

3 – Ground

Arming condition

Below 1 V

OK

Replace self power siren.

NG

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DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–467

LEXUS RX300 (RM785E)

3

Check harness and connector between ECU and alarm, alarm and body ground
(See page IN–32).

NG

Repair or replace harness or connector.

OK

Proceed to next circuit inspection shown in
problem symptom table (See page DI–452).