DTC B1208 Passenger Side Outer Mirror ECU

DESCRIPTION

This DTC is detected when communication between the outer mirror control ECU (passenger side outer mirror ECU) and gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1208	Outer mirror control ECU (passenger side) communication stops	Outer mirror control ECU (passenger side) Wire harness

WIRING DIAGRAM

Dtc B1208 Passenger Side Outer Mirror Ecu. 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 B1208, repair the "+B or GND short malfunction of communication bus" DTCs first.

1.INSPECT FUSE (FR DOOR RH (LHD), FR DOOR LH (RHD), MPX-B)

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

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

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

Measure the resistance of the fuse.

Standard resistance:
Below 1 Ω

REPLACE FUSE

OK

2.CHECK WIRE HARNESS (OUTER MIRROR CONTROL ECU - BATTERY AND BODY GROUND)

Disconnect the M10 ECU connector (for LHD).

Dtc B1208 Passenger Side Outer Mirror Ecu. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

Disconnect the L10 ECU connector (for RHD).

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

Standard voltage:
Tester Connection Condition Specified Condition
^*1BDR (M10-6) - Body ground
^*2BDR (L10-6) - Body ground Always 10 to 14 V
^*1CPUB (M10-4) - Body ground
^*2CPUB (L10-4) - Body ground Always 10 to 14 V

Standard resistance:
Tester Connection Specified Condition
^*1GND (L10-1) - Body ground
^*2GND (M10-1) - Body ground Below 1 Ω

HINT:

*1: LHD

*2: RHD

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3.CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the M10 and J55 ECU connectors (for LHD).

Disconnect the L10 and P33 ECU connector (for RHD).

Dtc B1208 Passenger Side Outer Mirror Ecu. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

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

Standard resistance:
Tester Connection Specified Condition
^*1MPX1 (M10-8) - MPX2 (J55-24)
^*2MPX1 (L10-8) - MPX1 (P33-27) Below 1 Ω
^*1MPX1 (M10-8) - Body ground
^*2MPX1 (L10-8) - Body ground 10 kΩ or higher

HINT:

*1: LHD

*2: RHD

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE OUTER MIRROR CONTROL ECU (PASSENGER SIDE)

Tester Connection	Condition	Specified Condition
^1BDR (M10-6) - Body ground ^2BDR (L10-6) - Body ground	Always	10 to 14 V
^1CPUB (M10-4) - Body ground ^2CPUB (L10-4) - Body ground	Always	10 to 14 V

Tester Connection	Specified Condition
^1GND (L10-1) - Body ground ^2GND (M10-1) - Body ground	Below 1 Ω

Tester Connection	Specified Condition
^1MPX1 (M10-8) - MPX2 (J55-24) ^2MPX1 (L10-8) - MPX1 (P33-27)	Below 1 Ω
^1MPX1 (M10-8) - Body ground ^2MPX1 (L10-8) - Body ground	10 kΩ or higher