ECM Power Source Circuit: Wiring Diagram

1. Turn the ignition switch ON.
2. Measure the voltage of the ECM connectors.

   standard voltage 

OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE 

Fig 2: Checking ECM (+B Voltage)

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NG 

1. Disconnect the negative battery cable.
2. Disconnect the E6 ECM connector.
3. Measure the resistance of the wire harness side connectors.

Standard resistance 

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

Fig 3: Disconnecting E6 ECM Connector

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OK : Go to next Step 

1. Turn the ignition switch ON.
2. Measure the voltage of the ECM connectors.

   standard voltage 

OK : GO TO STEP   6 

Fig 4: Checking ECM (IGSW Voltage)

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NG 

1. Remove the AM2 fuse from the engine room relay block.
2. Measure the resistance of the AM2 fuse.

Standard resistance: 

Below 1 Ω 

NG : CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE 

Fig 5: Removing AM2 Fuse From Engine Room Relay Block

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OK : Go to next Step 

1. Disconnect the I5 ignition switch connector.
2. Measure the resistance of the switch.

Standard resistance 

NG : REPLACE IGNITION SWITCH ASSEMBLY 

Fig 6: Identifying Ignition Switch Connector Terminals

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OK : CHECK AND REPLACE HARNESS AND CONNECTOR (BATTERY - IGNITION SWITCH, IGNITION SWITCH - ECM) 

1. Turn the ignition switch ON.
2. Measure the voltage of the ECM connectors.

   standard voltage 

NG : REPLACE ECM 

Fig 7: Checking ECM (MREL Voltage)

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OK : Go to next Step 

1. Remove the EFI fuse from the engine room relay block.
2. Measure the resistance of the EFI fuse.

Standard: 

Below 1 Ω 

NG : CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE 

Fig 8: Removing EFI Fuse From Engine Room Relay Block

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OK : Go to next Step 

1. Remove the EFI relay from the engine room relay block.
2. Check the resistance of the EFI relay.

Standard resistance 

NG : REPLACE EFI RELAY 

Fig 9: Identifying EFI Relay Terminals

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OK : Go to next Step 

1. Check the wire harness between the EFI relay and ECM.
   1. Remove the EFI relay from the engine room relay block.
   2. Disconnect the E4 ECM connector.
   3. Measure the resistance of the wire harness side conectors.

   Standard resistance 

   TESTER CONNECTION SPECIFIED CONDITION CHART
   
   

   Tester Connection	Specified Condition
   Engine room relay block (EFI relay terminal 1) - MREL (E4-8)	Below 1 Ω
   Engine room relay block (EFI relay terminal 3) - +B (E4-1)	Below 1 Ω
   Engine room relay block (EFI relay terminal 1) or MREL (E4-8) - Body ground	10 kΩ or higher
   Engine room relay block (EFI relay terminal 3) or +B (E4-1) - Body ground	10 kΩ or higher

2. Check the wire harness between the EFI relay and body ground.
   1. Remove the EFI relay from the engine room relay block.
   2. Measure the resistance of the wire harness side connector.

      Standard resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester Connection	Specified Condition
      Engine room relay block (EFI relay terminal 2) - Body ground	Below 1 Ω

   3. Reinstall the EFI relay.

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

Fig 10: Removing EFI Relay From Engine Room Relay Block

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL 5 OF EFI RELAY - BATTERY POSITIVE TERMINAL)