Dtc B1200 Mpx Body Ecu Stop

Lexus IS250 IS220d GSE20 ALE20 - MULTIPLEX COMMUNICATION

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT FUSE (FR DOOR RH)

CHECK WIRE HARNESS (MAIN BODY ECU RH - BATTERY AND BODY GROUND)

CHECK RESISTANCE OF COMMUNICATION LINE

DTC B1200 MPX Body ECU Stop

DESCRIPTION

This DTC is detected when communication between the main body ECU RH (cowl side J/B RH) and gateway ECU stops for more than 10 seconds.
DTC No.DTC Detection ConditionTrouble Area
B1200Main body ECU RH (cowl side J/B RH) communication stops
Main body ECU RH (cowl side J/B RH)
Wire harness

WIRING DIAGRAM

Dtc B1200 Mpx Body Ecu Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

  • HINT:
  • When "+B of GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTC B1200, repair the "+B or GND short malfunction of communication bus" DTCs first.
1.INSPECT FUSE (FR DOOR RH)

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

Measure the resistance of the fuse.

  • Standard resistance:
  • Below 1 Ω
NG
REPLACE FUSE
OK
2.CHECK WIRE HARNESS (MAIN BODY ECU RH - BATTERY AND BODY GROUND)

Disconnect the main body ECU RH (cowl side J/B RH) connector.

Dtc B1200 Mpx Body Ecu Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

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

  • Standard voltage:
  • Tester ConnectionConditionSpecified Condition
    BATB (RN-1) - Body groundAlways10 to 14 V
  • Standard resistance:
  • Tester ConnectionSpecified Condition
    GND2 (RD-7) - Body groundBelow 1 Ω
    GND1 (RD-17) - Body groundBelow 1 Ω
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
3.CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the J75, J76, P33 and RJ ECU connectors (for LHD).

Disconnect the L17, RJ, J75 and J76 ECU connector (for RHD).

Dtc B1200 Mpx Body Ecu Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

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

  • Standard resistance:
  • Tester ConnectionSpecified Condition
    MPX2 (J75-21) - MPD1 (J76-3)Below 1 Ω
    *1MPX1 (RJ-21) - MPX1 (P33-27)
    *2MPX1 (RJ-21) - MPX2 (L17-8)    		Below 1 Ω
  • HINT:
*1: LHD
*2: RHD
  • Result:
  • ResultProceed to
    Both are OKA
    One is OKB
    Both are NGC
B
REPLACE MAIN BODY ECU RH AND REPAIR OR REPLACE HARNESS OR CONNECTOR
C
REPAIR OR REPLACE HARNESS OR CONNECTOR
A
REPLACE MAIN BODY ECU RH (COWL SIDE JUNCTION BLOCK RH)