Lexus RX300 (MCU15). Service manual - part 309

I19248

Theft Deterrent ECU

IOUT

8

R–Y

5

R2
Radar Sensor
(in Interior Light)

2

T4

IJ1

W–B

S+B

18

T4

3

1

GND

4

W

IH

S+B

IOUT

R–Y

W

6

IJ1

3G

9

3H

J/B No. 3

W–B

DI–468

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

LEXUS RX300   (RM785E)

Radar Sensor (Europe)

CIRCUIT DESCRIPTION

A radio transmitter is in integrated into the doom light.
This creates a spherical electric field inside the vehicle detects intrusion using the Doppler effect caused by
movement of an object in the vehicle, and outputs a warning trigger signal to the theft deterrent ECU.

WIRING DIAGRAM

INSPECTION PROCEDURE

1

Check radar sensor operation.

CHECK:
Set the system with a window open, and after 30 seconds put
your hand through the window and shake it near the sensor to
check if the alarm is triggered.

OK

No problem.

NG

DI61J–02

I11491

1

2

3

4

5

Connector connected

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–469

LEXUS RX300   (RM785E)

2

Check radar sensor.

PREPARATION:
Remove the room light assembly.
CHECK:
Measure the voltage and continuity terminals.
OK:

Tester connection

Condition

Specified condition

1 – Ground

Arming preparation state

or armed state.

Battery voltage

1   Ground

Disarmed state.

Below 1 V

When the sensor does not

detect any movement.

6.8 V ± 2 V

2 – Ground

When the sensor detects

movement when in arming

preparation or armed

state.

Below 1 V

4 – Ground

Constant

Continuity

NG

Replace radar sensor. (in Room light assembly)

OK

3

Check harness and connector between ECU and sensor, sensor 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).

I11441

Theft Deterrent ECU

DSWH

T4

4

7

1

E3
Engine Hood
Courtesy S/W

2

W–B

EA

EC1

R–W

R–W

A

J/C

DI–470

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

LEXUS RX300   (RM785E)

Engine Hood Courtesy Switch Circuit

CIRCUIT DESCRIPTION

The engine hood courtesy switch is built into the engine hood lock assembly and goes ON when the engine
hood is opened and goes OFF when the engine hood is closed.

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 hood courtesy switch using hand–held tester.

PREPARATION:
Connect the hand–held tester to the DLC 3.
CHECK:
Check the hood courtesy switch using DATA LIST.

OK

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

NG

DI61H–04

N14878

1 (+)

2 (–)

–

DIAGNOSTICS

THEFT DETERRENT SYSTEM

DI–471

LEXUS RX300   (RM785E)

2

Check engine hood courtesy switch.

PREPARATION:
(a)

Remove engine hood lock assembly.

(b)

Disconnect engine hood courtesy switch connector.

CHECK:
Check continuity between terminals 1 and 2 when engine hood
lock is locked and unlocked.
OK:

Engine hood lock

Tester connection

Specified condition

LOCK

–

No continuity

UNLOCK

1 – 2

Continuity

NG

Replace engine hood courtesy switch.

OK

3

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

NG

Repair or replace harness or connector.

OK

Check and replace theft deterrent ECU (See
page IN–32).