Lexus RX300 (MCU15). Manual - part 373

DI–722

–

DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300   (RM785E)

DTC

B1273 / 73

Sliding roof ECU communication stop
(w/ Sliding roof vehicle only)

CIRCUIT DESCRIPTION

This DTC is output when communication stops between sliding roof ECU and body ECU.

DTC No.

DTC Detecting Condition

Trouble Area

B1273/73

No communication from sliding roof ECU more than 10 se-

S Sliding roof  ECU

B1273/73

No communication from sliding roof ECU more than 10 se

conds.

Sliding roof  ECU

S Wireharness

WIRING DIAGRAM

See page DI–688.

INSPECTION PROCEDURE

1

Check sliding roof ECU.

CHECK:
Check that the operation of the sliding roof function is normal.
HINT:
With this inspection, the sliding roof ECU CPU can be diagnosed if it works normally or not.

NG

Replace the sliding roof ECU.

OK

DI2BG–06

I07402

Body ECU

Sliding Roof

MPX1

MPX1

–

DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–723

LEXUS RX300   (RM785E)

2

Check wireharness

PREPARATION:
Disconnect connector sliding roof ECU and body ECU.
CHECK:
Check continuity between terminals MPX1 of body ECU and
MPX1 of sliding roof ECU.
OK:
There is a continuity in wireharness.

NG

Repair or replace wireharness.

OK

Replace the sliding roof ECU.

I19225

MPX–

MPX+

MPX–

MPX1

”I16”

”I17”

Theft Deterrent ECU

Center Cluster

”C11”

DI–724

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DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

LEXUS RX300   (RM785E)

DTC

B1276 / 76

A/C and combination meter integrated
ECU communication stop

CIRCUIT DESCRIPTION

This DTC is output when communication stops between A/C and combination meter integrated ECU and
Body ECU.

DTC No.

DTC Detecting Condition

Trouble Area

B1276/76

No communication from A/C and combination meter integrated

S A/C and combination meter integrated ECU

B1276/76

No communication from A/C and combination meter integrated

ECU more than 10 seconds.

A/C and combination meter integrated ECU

S Wireharness

WIRING DIAGRAM

See page DI–688

INSPECTION PROCEDURE

1

Check wireharness

PREPARATION:
Disconnect connector ”I16 (Except Europe)” or ”I17 (Europe)”
of center cluster integration panel ”T5” of theft deterrent ECU
and ”C11” of A/C and combination meter integrated ECU.
CHECK:
(a)

Check continuity between terminals MPX– of center clus-
ter integration panel and MPX+ of A/C and combination
meter integrated ECU.

(b)

Check continuity between terminals MPX– of A/C and
combination meter integrated ECU and MPX1 of theft de-
terrent ECU.

OK:
There is a continuity in wireharness of both (a) and (b), 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 the A/C  and combination meter inte-
grated ECU.

DI2BC–07

I19226

MPX–

MPX+

MPX–

MPX2

”B8”

”C11”

–

DIAGNOSTICS

MULTIPLEX COMMUNICATION SYSTEM

DI–725

LEXUS RX300   (RM785E)

DTC

B1277 / 77

Center cluster integration panel com-
munication stop

CIRCUIT DESCRIPTION

This DTC is output when communication stops between center cluster integration panel and Body ECU.

DTC No.

DTC Detecting Condition

Trouble Area

B1277/77

No communication from center cluster integration panel more

S Center cluster integration panel

B1277/77

No communication from center cluster integration  anel more

than 10 seconds.

Center cluster integration  anel

S Wireharness

WIRING DIAGRAM

See page DI–688

INSPECTION PROCEDURE

1

Check wireharness

PREPARATION:
Disconnect connector ”B8” of body ECU ”I16” or ”I17” of center
cluster integration panel and ”C11” of A/C and combination me-
ter integrated ECU.
CHECK:
(a)

Check continuity between terminals MPX2 of body ECU
and MPX+ of A/C and combination meter integrated ECU.

(b)

Check continuity between terminals MPX2 of body ECU
and MPX– of center cluster integration panel.

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 the A/C ECU.

DI2BC–08