Sfi System Ecm Power Source Circuit

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

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT ECM (+B, +B1 VOLTAGE)

CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)

INSPECT ECM (IGSW VOLTAGE)

CHECK FUSE (IGN FUSE)

INSPECT IG2 RELAY

INSPECT ECM (MREL VOLTAGE)

CHECK FUSE (EFI FUSE)

INSPECT INTEGRATION RELAY (EFI MAIN RELAY)

CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY- ECM, INTEGRATION RELAY - BODY GROUND)

SFI SYSTEM - ECM Power Source Circuit


DESCRIPTION

When the engine switch is turned to on, the 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 MAIN relay and supplying power to terminal +B of the ECM.
If the engine switch is turned to off, the ECM holds the EFI MAIN 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 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit


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


INSPECTION PROCEDURE

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

  1. Turn the engine switch on (IG).

  1. Measure the voltage between the terminals of the A6 and E7 ECM connectors.

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


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


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

  1. Disconnect the E7 ECM connector.

  1. Measure the resistance.

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

  1. Reconnect the ECM connector.



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


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

  1. Turn the engine switch on (IG).

  1. Measure the voltage between the terminals of the A6 and E7 ECM connectors.

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


OK
Go to step 6
NG


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

  1. Remove the IGN fuse from the cowl side junction block RH.

  1. Measure the resistance of the IGN fuse .

    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 IG2 RELAY
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Ecm Power Source Circuit

  1. Remove the IG2 relay from the 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 applied to terminals 1 and 2)


NG
REPLACE IG2 RELAY
OK

PUSH BUTTON START SYSTEM

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

  1. Turn the engine switch on (IG).

  1. Measure the voltage between the terminals of the A6 and E7 ECM connectors.

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


NG
REPLACE ECM
OK


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

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

  1. Measure the resistance of the EFI fuse .

    Standard resistance:
    Below 1 Ω

  1. Reinstall the EFI fuse.



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


8.INSPECT INTEGRATION RELAY (EFI MAIN RELAY)
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-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:
    Tester Connection
    		Specified Condition
    2C-1 - 2A-8
    		10 kΩ or higher
    Below 1 Ω
    (When battery voltage applied to terminals 2A-6 and 2A-7)


NG
REPLACE INTEGRATION RELAY
OK


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

  1. Check the harness and the connectors 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 between the wire harness side connectors.

      Standard resistance (Check for open):
      Tester Connection
      		Specified Condition
      2A-6 - MREL (A6-13)
      		Below 1 Ω
      Standard resistance (Check for short):
      Tester Connection
      		Specified Condition
      2A-6 or MREL (A6-13) - 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 No. 2 junction block.

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

      Standard resistance (Check for open):
      Tester Connection
      		Specified condition
      2A-7 - Body ground
      		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

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