Lexus RX300 (MCU15). Service manual — part 371

I12721

Body ECU

Wireless Door Lock Tuner

2

PRG

RDA

16

17

LG

LG

L

L

18

IA2

IA2

17

3

B6

B6

PRG

RDA

DI–714

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300 (RM785E)

DTC

B1244 / 44

Light sensor circuit malfunction

CIRCUIT DESCRIPTION

This DTC is output when failure of light sensor circuit is detected.

DTC No.

DTC Detecting Condition

Trouble Area

B1244/44

S Malfunction of light sensor

S Open or short of light sensor circuit

S Light sensor

S Wireharness

S Body ECU

WIRING DIAGRAM

DI2B9–09

–

DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–715

LEXUS RX300 (RM785E)

INSPECTION PROCEDURE

1

Check light sensor.

Using hand –held tester:
PREPARATION:
(a)

Connect the hand–held tester to the DLC3.

(b)

Turn ignition switch ON and hand–held tester main switch ON.

CHECK:
The value of the illumination rate should change in the following range when the light sensor is put in the
light or covered by a hand.
OK:

0.8 ms ∼ 22.0 ms

HINT:

S

This is the time to be taken for the light sensor to generate one cycle of frequency according to the
brightness.

S

Check it by putting the light control switch in AUTO position.

When not using hand–held tester. (See page BE–31)

NG

Replace the light sensor.

OK

2

Check wireharness and connector between light sensor and Body ECU.

NG

Repair or replace wireharness or connector.

OK

Replace the Body ECU.

DI–716

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300 (RM785E)

DTC

B1249 / 49

Double lock control relay communica-
tion stop

CIRCUIT DESCRIPTION

This DTC is output when communication stops between double lock control relay and Body ECU.

DTC No.

DTC Detecting Condition

Trouble Area

B1249/49

No communication from double lock control relay more than 10

S Double lock control relay

B1249/49

No communication from double lock control relay more than 10

seconds.

Double lock control relay

S Wireharness

WIRING DIAGRAM

See page DI–688

INSPECTION PROCEDURE

1

Check double lock control relay.

CHECK:
Check that the operation of double lock control relay is normal.
HINT:
With this inspection, the double lock control relay can be diagnosed if it works normally or not.

NG

Replace the double lock control relay.

OK

DI2BF–08

I19228

Double Lock Control

Rear RH Door

MPX1

MPX1

MPX1

MPX2

Double Lock Control

Rear RH Door

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–717

LEXUS RX300 (RM785E)

2

Check wireharness

PREPARATION:
Disconnect connector ”R15” of rear right door ECU, double lock
control relay and ”R13” of rear left door ECU.
CHECK:
(a)

Check continuity between terminals MPX1 of double lock
control relay and MPX2 of rear left door ECU.

(b)

Check continuity between terminals MPX1 of rear right
door ECU and MPX2 of double lock control relay.

OK:
There is a continuity in wireharness of both (a) and (b), or either
(a) or (b).
HINT:
If there is OPEN in wireharness of either (a) or (b), please repair
it.

NG

Repair or replace wireharness.

OK

Replace double lock control relay.