Sfi System Cranking Holding Function Circuit

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

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK OPERATION OF ENGINE CRANKING

READ VALUE OF INTELLIGENT TESTER (STARTER SIGNAL)

INSPECT ECM (STAR AND STSW VOLTAGE)

INSPECT ST CUT RELAY

INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY

INSPECT STARTER RELAY

CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - STARTER RELAY)

INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE)

INSPECT STARTER ASSEMBLY

CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM)

SFI SYSTEM - Cranking Holding Function Circuit


DESCRIPTION

The cranking holding control system provides current to the starter when the ECM detects the engine switch's start signal (STSW). When the ECM performs a firing judgment, the system cuts current to the starter. When an ECM receives the STSW signal, it turns on the ST CUT relay, which prevents flickering of the combination meter, clock, audio system, etc. Also, the ECM sends a signal to the ECM's STAR terminal. Then the STAR output signal travels through the park/neutral position (PNP) switch to the STARTER relay, causing the starter to activate.
When the engine is cranking, the starter operation signal is sent to the ECM's STA terminal.

Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit


WIRING DIAGRAM

Refer to DTC P0617 on page Click here.

INSPECTION PROCEDURE

1.CHECK OPERATION OF ENGINE CRANKING

  1. When turning the engine switch to the START position, check whether the starter motor starts.



OK
CHECK FOR INTERMITTENT PROBLEMS
NG


2.READ VALUE OF INTELLIGENT TESTER (STARTER SIGNAL)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG) and turn the tester ON.

  1. Enter the following menus: Powertarin / Engine / Data List / Starter Signal.

  1. Check the result when the engine switch is turned to on (IG) and START.

    Standard
    Engine Switch Position
    		ON (IG)
    		START
    Starter Signal
    		OFF
    		ON


OK
Go to step 6
NG


3.INSPECT ECM (STAR AND STSW VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

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

    Standard voltage:
    Tester Connection
    		Specified Condition
    STAR (E7-4) - E1 (E7-7)
    		9 to 14 V
    STSW (A6-19) - E1 (E7-7)
    		9 to 14 V

    Result:
    Terminal STAR
    		Terminal STSW
    		Proceed to
    9 to 14 V
    		9 to 14 V
    		A
    0 V
    		9 to 14 V
    		B
    0 V
    		0 V
    		C


B
REPLACE ECM

C
Go to step 10
A


4.INSPECT ST CUT RELAY
Lexus Gs430, Gs300. Uzs190 Grs190

  1. Remove the ST CUT relay from the engine room No. 2 relay block

  1. Measure the resistance of the ST CUT 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 ST CUT RELAY
OK


5.INSPECT PARK/NEUTRAL POSITION SWITCH ASSEMBLY
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

  1. Disconnect the E25 park/neutral position (PNP) switch connector.

  1. Measure the resistance between each terminal shown below when the shift lever is moved to each range.

    Standard resistance:
    Shift Position
    		Tester Connection
    		Specified Condition
    P
    		6 - 9
    		Below 1 Ω
    N
    		6 - 9
    		Below 1 Ω


NG
REPLACE PARK/NEUTRAL POSITION SWITCH
OK

CHECK AND REPAIR HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - ECM, ECM - ST CUT RELAY, ST CUT RELAY, ST CUT - PARK/NEUTRAL POSITION SWITCH)

6.INSPECT STARTER RELAY
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

  1. Remove the starter relay from the engine room No. 1 relay block.

  1. Measure the resistance of the starter 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 STARTER RELAY
OK


7.CHECK HARNESS AND CONNECTOR (PARK/NEUTRAL POSITION SWITCH - STARTER RELAY)
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

  1. Check the harness and the connectors between the park/neutral position switch and the starter relay.

    1. Disconnect the E25 PNP switch connector.

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

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

      Standard resistance (Check for open):
      Tester Connection
      		Specified Condition
      Park/Neutral position switch (E25-6) - Starter relay terminal (1)
      		Below 1 Ω
      Standard resistance (Check for short):
      Tester Connection
      		Specified Condition
      Park/Neutral position switch (E25-6) or Starter relay terminal (1) - Body ground
      		10 kΩ or higher

  1. Check the harness and the connector between the starter relay and the body ground.

    1. Remove the starter relay from the engine room No. 1 relay block.

    2. Measure the resistance between the starter relay and the body ground.

      Standard resistance (Check for open):
      Tester Connection
      		Specified Condition
      Starter relay terminal (2) - Body ground
      		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


8.INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE)
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

  1. Remove the starter relay from the engine room No. 1 relay block.

  1. Measure the voltage between the terminals of the engine room No. 1 relay block and the body ground.

    Standard voltage:
    Tester Connection
    		Specified Condition
    Starter relay terminal (5) - Body ground
    		9 to 14 V


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


9.INSPECT STARTER ASSEMBLY


NG
REPAIR OR REPLACE STARTER ASSEMBLY
OK

REPAIR OR REPLACE HARNESS AND CONNECTOR (STARTER RELAY - STARTER, STARTER - BATTERY)

10.CHECK HARNESS AND CONNECTOR (POWER SOURCE CONTROL ECU - ECM)
Lexus Gs430, Gs300. Uzs190 Grs190.3Gr-Fe Engine Control System.Sfi System.Sfi System Cranking Holding Function Circuit

  1. Check the harness and the connectors between the power source control ECU and ECM.

    1. Disconnect the L73 power source control ECU connector.

    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
      STSW (L73-39) - STSW (A6-19)
      		Below 1 Ω
      Standard resistance (Check for short):
      Tester Connection
      		Specified Condition
      STSW (L73-39) or STSW (A6-19) - Body ground
      		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

GO TO PUSH BUTTON START SYSTEM