Inspection Procedure

1. Disconnect the U28 ECU connector.
2. Measure the resistance and voltage of the wire harness side connector.

   Standard voltage 

   VOLTAGE SPECIFIED CONDITIONS
   
   

   Tester Connection	Specified Condition
   U28-1 (+B1) - Body ground	10 to 14 V

   Standard resistance 

   RESISTANCE SPECIFIED CONDITION
   
   

   Tester Connection	Specified Condition
   U28-17 (E) - Body ground	Below 1 Ω

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

Fig 1: Identifying U28 Certification ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : Go to next step 

Fig 2: Identifying A7, K66, M4 And U28 ECU Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the a7, K66, M4 and U28 ECU connectors.
2. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   RESISTANCE SPECIFIED CONDITION
   
   

   Tester Connection	Specified Condition
   U28-27 (MPX1) - M4-8 (MPX1)	Below 1 Ω
   U28-27 (MPX1) - a7-1 (MPX1)	Below 1 Ω
   U28-28 (MPX2) - K66-12 (MPD2)	Below 1 Ω

   Result 

   RESULT CHART
   
   

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

B : REPLACE CERTIFICATION ECU AND WIRE HARNESS CONNECTOR 

C : REPAIR OR REPLACE HARNESS AND CONNECTOR 

A : REPLACE CERTIFICATION ECU