DTC B1249 Double Locking ECU Communication Stop

DESCRIPTION

This DTC is detected when communication between the double door lock ECU and gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1262	Double door lock ECU communication stops	Double door lock ECU Wire harness

Dtc B1249 Double Locking 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" DTC B1249, repair the "+B or GND short malfunction of communication bus" DTCs first.

1.INSPECT FUSE (MPX-B, DOOR DL)

Remove the MPX-B fuse from the engine room J/B No. 1.

Remove the DOOR DL fuse from the main body ECU RH (cowl side J/B RH).

Measure the resistance of the fuse.

REPLACE FUSE

OK

2.CHECK WIRE HARNESS (DOUBLE DOOR LOCK ECU - BATTERY AND BODY GROUND)

Disconnect the P34 ECU connector.

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

Standard voltage:
Tester Connection Condition Specified Condition
+B (P34-1) - Body ground Always 10 to 14 V
CPUB (P34-7) - Body ground Always 10 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.CHECK COMMUNICATION LINE

Disconnect the P34 and P33 ECU connectors.

Measure the resistance of the wire harness side connector.

Standard resistance:
Tester Connection Specified Condition
MPX1 (P34-9) - MPX1 (P33-27) Below 1 Ω
MPX1 (P34-9) - Body ground 10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE DOUBLE DOOR LOCK ECU

Tester Connection	Specified Condition
GND (P34-14) - Body ground	Below 1 Ω