Dtc B1263 Luggage Room Junction Block Ecu Communication Stop

Communication System. Lexus Gs430, Gs300. Uzs190 Grs190
Multiplex Communication. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT FUSE (MPX-B, D/C CUT)

CHECK WIRE HARNESS (NO. 1 JUNCTION BLOCK ASSEMBLY - BATTERY AND BODY GROUND)

CHECK RESISTANCE OF COMMUNICATION LINE

DTC B1263 Luggage Room Junction Block ECU Communication Stop


DESCRIPTION

This DTC is detected when communication between the No.1 junction block assembly (multiplex network rear ECU) and network gateway ECU stops for more than 10 seconds.

DTC No.
DTC Detection Condition
Trouble Area
B1263
No.1 junction block assembly (multiplex network rear ECU) communication stops
  1. No.1 junction block assembly (multiplex network rear ECU)
  2. Wire harness

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1263 Luggage Room Junction Block Ecu Communication Stop


INSPECTION PROCEDURE

1.INSPECT FUSE (MPX-B, D/C CUT)

  1. Remove the MPX-B and D/C CUT fuses from the engine room No. 1 relay block.

  1. Measure the resistance of the fuses.



NG
REPLACE FUSE
OK


2.CHECK WIRE HARNESS (NO. 1 JUNCTION BLOCK ASSEMBLY - BATTERY AND BODY GROUND)

Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1263 Luggage Room Junction Block Ecu Communication Stop

  1. Disconnect the LC and LF junction block connectors.

  1. Measure the resistance and voltage of the wire harness side connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    LC-15 (ECUB) - Body ground
    		10 to 14 V
    Standard resistance:
    Tester Connection
    		Specified Condition
    LF-1 (PGND) - Body ground
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK RESISTANCE OF COMMUNICATION LINE

Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1263 Luggage Room Junction Block Ecu Communication Stop

  1. Disconnect the L66 connector.

  1. Disconnect the V3 and LC junction block connectors.

  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    LC-21 (MPX1) - L66-5 (MPL1)
    		Below 1 Ω
    LC-31 (MPX2) - W3-15 (MPX1)
    		Below 1 Ω
    Result:
    Result
    		Proceed to
    Both are OK
    		A
    One is OK
    		B
    Both are NG
    		C


B
REPLACE NO. 1 JUNCTION BLOCK AND HARNESS AND CONNECTOR

C
REPAIR OR REPLACE HARNESS AND CONNECTOR
A

REPLACE NO. 1 JUNCTION BLOCK ASSEMBLY