ECU Power Source Circuit: Procedure

1. Remove the ECU-IG fuse from the main body ECU.
   Fig 1: Locating ECU-IG Fuse Of Main Body ECU

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2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   ECU-IG	Always	Below 1 Ω

NG → See step   4 

OK: Go to next step 

1. Disconnect the E74 ECU connector.
   Fig 2: Identifying IG Terminal Of E74 ECU Connector

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2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   E74-7 (IG) - Body ground	Ignition switch ON	11 to 14 V
   	Ignition switch OFF	Below 1 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the E74 ECU connector.
   Fig 3: Identifying GND Terminal Of E74 ECU Connector

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2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   E74-9 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   5 

1. Disconnect the E74 ECU connector.
   Fig 4: Identifying IG Terminal Of E74 ECU Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Switch Condition	Specified Condition
   E74-7 (IG) - Body ground	Ignition switch OFF	10 kΩ or higher

NG → REPLACE FUSE AND REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE FUSE