DTC B1273 Sliding Roof ECU Communication Stop

DESCRIPTION

This DTC is detected when communication between the sliding roof control ECU and gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1273	Sliding roof control ECU communication stops	Sliding roof control ECU Wire harness

Dtc B1273 Sliding Roof Ecu Communication Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

When "+B of GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTCB1273, repair the "+B or GND short malfunction of communication bus" DTCs first.

1.INSPECT FUSE (S/ROOF)

Remove the S/ROOF fuse from the main body ECU LH (cowl side J/B LH).

Measure the resistance of the fuse.

REPLACE FUSE

OK

2.CHECK WIRE HARNESS (SLIDING ROOF CONTROL ECU - BATTERY AND BODY GROUND)

Disconnect the R6 ECU connector.

Measure the voltage and resistance of the wire harness side connector.

Standard voltage:
Tester Connection Condition Specified Condition
B (R6-5) - Body ground Always 10 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the R6 and R5 connectors.

Measure the resistance between the specified terminals on the wire harness side connectors.

Standard resistance:
Tester Connection Specified Condition
MPX1 (R6-10) - MPX2 (R5-38) Below 1 Ω
MPX1 (R6-10) - Body ground 10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE SLIDING ROOF CONTROL ECU

Tester Connection	Condition	Specified Condition
B (R6-5) - Body ground	Always	10 to 14 V

Tester Connection	Specified Condition
E (R6-7) - Body ground	Below 1 Ω