Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1205

Diagnostic trouble codes

DESCRIPTION

  1. This DTC is detected when communication between the AFS ECU and the gateway ECU stops for more than 10 seconds.
DTC No.
 DTC Detection Condition
 Trouble Area
B1205
 AFS ECU communication stops
  1. AFS ECU
  2. Wire harness

WIRING DIAGRAM

B110889E01

INSPECTION PROCEDURE

HINT:
When "+B of GND short malfunction of communication bus" DTCs (B1266 and B1267) are detected at the same time as "communication stop" DTC B1205, repair the "+B or GND short malfunction of communication bus" DTCs first.


1. INSPECT FUSE (H-LP LVL)

  1. Remove the H-LP LVL fuse from the main body ECU LH (cowl side J/B LH).

  1. Measure the resistance of the fuse.

    Standard resistance:
    Below 1 Ω



 NG
REPLACE FUSE
OK


2. CHECK WIRE HARNESS (AFS ECU - BATTERY AND BODY GROUND)

  1. B110946E01
    Disconnect the A27 ECU connector.

  1. Turn the engine switch on (IG).

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    IG (A27-2) - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V

    Standard resistance:
    Tester Connection
    		 Specified Condition
    E1 (A27-1) - Body ground
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3. CHECK RESISTANCE OF COMMUNICATION LINE

  1. B110947E01
    Disconnect the A27, J58 and J34 ECU connectors.

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

    Standard resistance:
    Tester Connection
    		 Specified Condition
    MPX1 (A27-5) - MPX- (J58-31)
    		 Below 1 Ω
    MPX2 (A27-6) - MPX+ (J34-6)
    		 Below 1 Ω

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



B
REPLACE AFS ECU AND REPAIR OR REPLACE HARNESS OR CONNECTOR

C
REPAIR OR REPLACE HARNESS OR CONNECTOR
A

REPLACE AFS ECU


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