Sfi System Ecm Power Source Circuit

Engine. Lexus Gs430, Gs300. Uzs190 Grs190
3Uz-Fe Engine Control System. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK ECM (+B, +B1 VOLTAGE)

CHECK WIRE HARNESS (ECM - BODY GROUND)

CHECK ECM (IGSW VOLTAGE)

INSPECT FUSE (IGN)

INSPECT RELAY (Marking: IG2)

CHECK ECM (MREL VOLTAGE)

INSPECT FUSE (EFI)

INSPECT INTEGRATION RELAY (Marking: EFI MAIN)

CHECK WIRE HARNESS (INTEGRATION RELAY - ECM, INTEGRATION RELAY - BODY GROUND)

SFI SYSTEM - ECM Power Source Circuit


DESCRIPTION

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

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit


Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit


INSPECTION PROCEDURE

1.CHECK ECM (+B, +B1 VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Turn the engine switch on (IG).

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    A6-6 (+B) - E7-7 (E1)
    		9 to 14 V
    A6-5 (+B1) - E7-7 (E1)
    		9 to 14 V


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


2.CHECK WIRE HARNESS (ECM - BODY GROUND)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Disconnect the E7 ECM connector.

  1. Measure the resistance of the wire harness side connector.

    Standard resistance:
    Tester Connection
    		Specified Condition
    E7-7 (E1) - Body ground
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK ECM (IGSW VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Turn the engine switch on (IG).

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    A6-17 (IGSW) - E7-7 (E1)
    		9 to 14 V


OK
Go to step 6
NG


4.INSPECT FUSE (IGN)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Remove the IGN fuse from the body ECU.

  1. Measure the resistance of the IGN fuse.

    Standard resistance:
    Below 1 Ω


NG
CHECK AND REPLACE HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU, POWER SOURCE CONTROL ECU - ECM)
OK


5.INSPECT RELAY (Marking: IG2)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Remove the IG2 relay from engine room No. 2 relay block.

  1. Measure the resistance of the IG2 relay.

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


NG
REPLACE STARTER RELAY
OK

PUSH BUTTON START SYSTEM

6.CHECK ECM (MREL VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Turn the engine switch on (IG).

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    A6-13 (MREL) - E7-7 (E1)
    		9 to 14 V


NG
REPLACE ECM
OK


7.INSPECT FUSE (EFI)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Remove the EFI fuse from the engine room No. 2 relay block.

  1. Measure the resistance of the EFI fuse.

    Standard resistance:
    Below 1 Ω


NG
CHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED
OK


8.INSPECT INTEGRATION RELAY (Marking: EFI MAIN)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Remove the integration relay from the engine room No. 2 junction block.

  1. Measure the resistance of the EFI MAIN relay.

    Standard resistance:
    Terminal Connections
    		Specified Condition
    2A-8 - 2C-1
    		10 kΩ or higher
    2A-8 - 2C-1
    		Below 1 Ω
    (when battery voltage is applied to terminals 2A-6 and 2A-7)


NG
REPAIR POWER SOURCE CONTROL ECU
OK


9.CHECK WIRE HARNESS (INTEGRATION RELAY - ECM, INTEGRATION RELAY - BODY GROUND)
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Check the wire harness between the integration relay and the ECM.

    1. Remove the integration relay from the engine room No. 2 junction block

    2. Disconnect the A6 ECM connector.

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

      Standard resistance:
      Tester Connection
      		Specified Condition
      2A-6 - A6-13 (MREL)
      		Below 1 Ω
      2A-6 or A6-13 (MREL) - Body ground
      		10 kΩ or higher

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

    1. Remove the integration relay from the engine room No. 2 junction block.

    2. Measure the resistance of the wire harness side connectors.

      Standard resistance:
      Tester Connection
      		Specified Condition
      2A-7 - Body ground
      		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPAIR OR REPLACE HARNESS AND CONNECTOR (TERMINAL +B OF ECM - POSITIVE BATTERY (+) TERMINAL)