DTC B1280: Left Side Junction Block ECU Communication Stop: Procedure

1. Remove the MPX-B from the engine room J/B No. 1.
2. Measure the resistance of the fuse.

   Standard resistance

   Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

1. Disconnect the LD ECU connector.

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

   Standard voltage

   Tester Connection	Condition	Specified Condition
   MPXB (LD-18) - Body ground	Always	10 to 14 V

   Standard resistance

   Tester Connection	Specified Condition
   GND (LD-3) - Body ground	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the Q3, A30, M17 and 2F ECU connectors.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard resistance

   Tester Connection	Specified Condition
   MPX1 (Q3-15) - MPX1 (M17-3)	Below 1 Ω
   MPX2 (A30-17) - 2F-6	Below 1 Ω

   Result

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

B → REPAIR OR REPLACE HARNESS OR CONNECTOR AND REPLACE MAIN BODY ECU LH 

C → REPAIR OR REPLACE HARNESS OR CONNECTOR 

A → REPLACE MAIN BODY ECU LH