Lexus RX300 (MCU15). Manual - part 369

DI–706

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300   (RM785E)

DTC

B1217 / 17

Rear left door ECU communication
stop

CIRCUIT DESCRIPTION

This DTC is output when communication stops between rear left door ECU and body ECU.

DTC No.

DTC Detecting Condition

Trouble Area

B1217/17

No communication from rear left door ECU more than 10 se-

S Rear left door ECU

B1217/17

No communication from rear left door ECU more than 10 se

conds.

Rear left door ECU

S Wireharness

WIRING DIAGRAM

See page DI–688

INSPECTION PROCEDURE

1

Check rear left door ECU.

CHECK:
Check if the rear left door window glass auto up.
HINT:
With this inspection rear left door ECU CPU can be diagnosed if it works normal or not.

NG

Replace the rear left door ECU.

OK

DI2B4–07

I19224

”R13”

Rear Left Door

Rear Left Door

Double Lock 
Control Relay

Driver Door

”R13”

MPX2

MPX1

MPX2

MPX1

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–707

LEXUS RX300   (RM785E)

2

Check wireharness

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

Check continuity between terminals MPX2 of driver door
ECU and MPX1 of rear left door ECU.

(b)

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

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

NG

Repair or replace wireharness.

OK

Replace the rear left door ECU.

DI–708

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300   (RM785E)

DTC

B1221 / 21

Power window switch circuit on driver
door

DTC

B1222 / 22

Door lock switch circuit on driver door

DTC

B1223 / 23

Power window switch circuit on pas-
senger door

DTC

B1224 / 24

Door lock switch circuit on passenger
door

DTC

B1225 / 25

Power window switch circuit on rear
right door

DTC

B1226 / 26

Power window switch circuit on rear
left door

DTC

B1241 / 41

Body ECU switch circuit diagnosis

DTC

B1256 / 56

Center cluster integration panel switch
circuit diagnosis

CIRCUIT DESCRIPTION

These DTC notify how switch works as follows:
If DTC is not output when operating switch, it means failure of switch contact. If DTC is output when not oper-
ating switch, it means stick of switch. When something wrong is found by this diagnosis, inspect each switch.
Then, replace the switch if there is a problem, or check the wireharness if there is no problem.

DTC No.

DTC Detecting Condition

Trouble Area

B1221/21

Stick of either of the power window master switch 

(except window lock switch)

S Power window master switch

S Wireharness

B1222/22

Stick of door key lock and unlock switch

S Door lock control switch

S Door key lock and unlock switch

S Wireharness

DI2B6–09

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–709

LEXUS RX300   (RM785E)

B1223/23

Stick of passenger power window switch or door lock control

S Power window switch

S Door lock control switch

S Wireharness

B1224/24

Stick of door key lock and unlock switch

S Door lock control switch

S Door key lock and unlock switch

S Wireharness

B1225/25

Stick of rear right power window switch

S Power window switch

S Wireharness

B1226/26

Stick of rear left power window switch

S Power window switch

S Wireharness

B1241/41

Stick of switch

S Driver’s seat belt buckle switch

S Light control switch

S Stop light switch

S Wireharness

B1256/56

Stick of switch

S Multi function switch

S Power switch

S Sound mode switch

S Clock switch

S CD switch

S TAPE switch

S FM1/2 switch

S AM switch

S INFO switch

S BRIGHTNESS switch

S TUNE SEEK TRAC switch

S Eject switch

S MUTE switch

S MODE switch

S A/C switch

S R/F switch

S REAR defogger switch

S FRONT defroster switch

S OFF switch

S AUTO switch

S Wireharness

HINT:
Please refer to BE section for switch inspection, and to each door system of DI section for wireharness in-
spection.