SFI SYSTEM > ECM Power Source Circuit

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DESCRIPTION

When the engine switch is turned to on, the battery voltage is applied to terminal IGSW of the ECM (Included in HV Control ECU). The ECM MREL output signal causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the IGCT relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the ignition switch is turned ON, voltage from the ECM's MREL terminal flows to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the ECM.

WIRING DIAGRAM


A110933E03


INSPECTION PROCEDURE

1.INSPECT HV CONTROL ECU (+B, +B1 VOLTAGE)


    A103828E82

  1. Turn the ignition switch ON.

  1. Measure the voltage between the terminals of the H31 and H32 HV Control ECU connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    +B1 (H31-2) - E1 (H32-5)
    		9 to 14 V
    +B2 (H31-1) - E1 (H32-5)
    		9 to 14 V



OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE
NG


2.CHECK HARNESS AND CONNECTOR (HV CONTROL ECU - BODY GROUND)


    A107158E03

  1. Disconnect the H32 HV Control ECU connector.

  1. Measure the resistance between the HV Control ECU and body ground.

    Standard resistance (Check for open):
    Tester Connection
    		Specified Condition
    E1 (H32-5) - Body ground
    		Below 1 Ω

  1. Reconnect the HV Control ECU connector.



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.INSPECT HV CONTROL ECU (IGSW VOLTAGE)


    A103828E83

  1. Turn the ignition switch ON.

  1. Measure the voltage between the terminals of the H29 and H32 HV Control ECU connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    IGSW (H29-9) - E1 (H32-5)
    		9 to 14 V



OK
Go to step 6
NG


4.CHECK FUSE (IGN FUSE)


    A109151E01

  1. Remove the IGN fuse from the instrument panel J/B.

  1. Measure the IGN fuse resistance.

    Standard resistance:
    Below 1 Ω

  1. Reinstall the IGN fuse.



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


5.INSPECT IGNITION SWITCH ASSEMBLY


    A056879E02

  1. Check for continuity between the connector terminals shown in the chart below.

    Standard:
    Switch
    		Terminal No.
    		Resistance
    LOCK
    		All Terminals
    		No continuity
    ACC
    		1 - 2
    		Continuity
    ON
    		2 - 3, 2 - 4, 3 - 4, 6 - 7
    		Continuity
    START
    		1 - 2, 1 - 4, 2 - 4, 6 - 7, 6 - 8, 7 - 8
    		Continuity



NG
REPLACE IGNITION SWITCH ASSEMBLY
OK

PUSH HARNESS AND CONNECTOR (IGNITION SWITCH ASSEMBLY - HV CONTROL ECU) 

6.INSPECT HV CONTROL ECU (MREL VOLTAGE)


    A103828E84

  1. Turn the ignition switch ON.

  1. Measure the voltage between the terminals of the H31 and H32 HV Control ECU connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    MREL (H31-12) - E1 (H32-5)
    		9 to 14 V



NG
REPLACE HYBRID VEHICLE CONTROL ECU
OK


7.CHECK FUSE (IGCT NO.2 FUSE)


    A109152E01

  1. Remove the IGCT No.2 fuse from the R/B No.3.

  1. Measure the IGCT No.2 fuse resistance.

    Standard resistance:
    Below 1 Ω

  1. Reinstall the IGCT No.2 fuse.



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


8.INSPECT IGCT RELAY


    A092673

  1. Remove the integration relay from the engine room R/B.

  1. Measure the IGCT relay resistance.

    Standard resistance:
    Tester Connection
    		Specified Condition
    3 - 5
    		10 kΩ or higher
    Below 1 Ω
    (Apply battery voltage between terminals 1 and 2)



NG
REPLACE INTEGRATION RELAY
OK


9.CHECK HARNESS AND CONNECTOR (IGCT RELAY- HV CONTROL ECU, IGCT RELAY - BODY GROUND)


    A110914E03

  1. Check the harness and the connectors between the integration relay and the HV Control ECU.

    1. Remove the IGCT relay from the engine room R/B.

    2. Disconnect the H31 HV Control ECU connector.

    3. Measure the resistance between the wire harness side connectors.

      Standard resistance (Check for open):
      Tester Connection
      		Specified Condition
      IGCT relay (1)- MREL (H31-12)
      		Below 1 Ω

      Standard resistance (Check for short):
      Tester Connection
      		Specified Condition
      IGCT relay (1) or MREL (H31-12) - Body ground
      		10 kΩ or higher

  1. Check the harness and the connectors between the integration relay and body ground.

    1. Remove the integration relay from the engine room R/B.

    2. Measure the resistance between the wire harness side connector and body ground.

      Standard resistance (Check for open):
      Tester Connection
      		Specified condition
      IGCT relay (2) - Body ground
      		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL +B OF HV CONTROL ECU - BATTERY POSITIVE TERMINAL)