Lexus IS250 IS220d GSE20 ALE20 - MULTIPLEX COMMUNICATION

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT FUSE (FR P/SEAT LH (LHD), FR P/SEAT RH (RHD), MPX-B)

CHECK WIRE HARNESS (POSITION CONTROL ECU AND SWITCH - BATTERY AND BODY GROUND)

CHECK RESISTANCE OF COMMUNICATION LINE

DTC B1272 Power Seat ECU Communication Stop

DESCRIPTION

This DTC is detected when communication between the position control ECU and switch (driver seat ECU) and gateway ECU stops for more than 10 seconds.

DTC No.DTC Detection ConditionTrouble Area
B1272Position control ECU and switch (driver seat ECU) communication stops
Position control ECU and switch (driver seat ECU)
Wire harness

WIRING DIAGRAM

Dtc B1272 Power Seat Ecu Communication Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

Dtc B1272 Power Seat Ecu Communication 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 B1272, repair the "+B or GND short malfunction of communication bus" DTCs first.
1.INSPECT FUSE (FR P/SEAT LH (LHD), FR P/SEAT RH (RHD), MPX-B)

Remove the FR P/SEAT LH fuse from the main body ECU LH (cowl side J/B LH) (for LHD).

Remove the FR P/SEAT RH fuse from the main body ECU RH (cowl side J/B RH) (for RHD).

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

Measure the resistance of the fuses.

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

Disconnect the U6 and U7 ECU connectors (for LHD).

Dtc B1272 Power Seat Ecu Communication Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

Disconnect the T6 and T7 ECU connectors (for RHD).

Measure the voltage and resistance of the wire harness side connector

  • Standard voltage:
  • Tester ConnectionConditionSpecified Condition
    *1SYSB (U7-8) - Body ground
    *2SYSB (T7-8) - Body ground    		Always10 to 14 V
    *1+B (U6-5) - Body ground
    *2+B (T6-5) - Body ground    		Always10 to 14 V
  • HINT:
*1: LHD
*2: RHD
  • Standard resistance:
  • Tester ConnectionSpecified Condition
    *1GND (U6-1) - Body groundBelow 1 Ω
    *2GND (T6-1) - Body groundBelow 1 Ω
  • HINT:
*1: LHD
*2: RHD
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
3.CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the U7, 2F and J55 ECU connectors (for LHD).

Disconnect the T7, L17 and P33 ECU connectors (for RHD).

Dtc B1272 Power Seat Ecu Communication 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
    *1MPX1 (U7-1) - 2F-5
    *2MPX1 (T7-1) - MPX1 (L17-7)    		Below 1 Ω
    *1MPX1 (U7-1) - MPX2 (J55-24)
    *2MPX1 (T7-1) - MPX1 (P33-27)    		Below 1 Ω
  • HINT:
*1: LHD
*2: RHD
  • Result:
  • ResultProceed to
    Both are OKA
    One is OKB
    Both are NGC
B
REPAIR OR REPLACE HARNESS OR CONNECTOR AND REPLACE POSITION CONTROL ECU
C
REPAIR OR REPLACE HARNESS OR CONNECTOR
A
REPLACE POSITION CONTROL ECU AND SWITCH
LEXUS IS250, IS220d / GSE20 ALE20
MULTIPLEX COMMUNICATION
Lexus IS250 IS220d GSE20 ALE20
MULTIPLEX COMMUNICATION SYSTEM