Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1200

Diagnostic trouble codes

DESCRIPTION

  1. 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 Condition
 Trouble Area
B1200
 Main body ECU RH (cowl side J/B RH) communication stops
  1. Main body ECU RH (cowl side J/B RH)
  2. Wire harness

WIRING DIAGRAM

B133422E01

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)

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

  1. 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)

  1. Disconnect the main body ECU RH (cowl side J/B RH) connector.B110944E03

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    BATB (RN-1) - Body ground
    		 Always
    		 10 to 14 V

    Standard resistance:
    Tester Connection
    		 Specified Condition
    GND2 (RD-7) - Body ground
    		 Below 1 Ω
    GND1 (RD-17) - Body ground
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3. CHECK RESISTANCE OF COMMUNICATION LINE

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

  1. Disconnect the L17, RJ, J75 and J76 ECU connector (for RHD).B133213E01

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

    Standard resistance:
    Tester Connection
    		 Specified 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. *1: LHD
    2. *2: RHD

    Result:
    Result
    		 Proceed to
    Both are OK
    		 A
    One is OK
    		 B
    Both are NG
    		 C



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)


← DIAGNOSTIC TROUBLE CODE CHARTB1205 →