DTC B1271: Combination Meter ECU Communication Stop: Procedure

1. Remove the DOME and MPX-B fuses 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 J34 ECU connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard voltage

   Tester Connection	Condition	Specified Condition
   B (J34-23) - Body ground	Always	10 to 14 V
   B (J34-24) - Body ground	Always	10 to 14 V

   Standard resistance

   Tester Connection	Specified Condition
   E2 (J34-1) - Body ground	Below 1 Ω
   ES (J34-13) - Body ground	Below 1 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Combination Meter Assembly)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the J34, J49, J76 and J58 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
   MPX- (J34-18) - MPX1 (J49-3)*1	Below 1 Ω
   MPX- (J34-18) - MPI1 (J76-4)*2	Below 1 Ω
   MPX+ (J34-6) - MPX- (J58-31)	Below 1 Ω

   *1: w/ Tire Pressure Warning System

   *2: w/o Tire Pressure Warning System

   Result

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

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Combination Meter ECU)
   *2	Front view of wire harness connector (to Tire Pressure Monitor ECU)
   *3	Front view of wire harness connector (to Gateway ECU)
   *4	Front view of wire harness connector (to Air Conditioning Amplifier)

B → REPLACE COMBINATION METER ECU AND REPAIR OR REPLACE HARNESS OR CONNECTOR 

C → REPAIR OR REPLACE HARNESS OR CONNECTOR 

A → REPLACE COMBINATION METER ECU