Lexus IS250 · Service Manual ENGINE

Power Mode does not Change to ON (IG and ACC)

Circuit diagnosis

DESCRIPTION

When the engine switch is pushed with the electrical key in the cabin, the power source control ECU receives signals to switch the power source mode.

HINT:
To allow use of the intelligent tester to inspect the entry and start system when the engine switch is off, repeat opening and closing any of the doors. Opening and closing a door establishes communication between the intelligent tester and the power source control ECU. (Opening and closing a door can also be simulated by operating a door courtesy light switch.)


WIRING DIAGRAM

B112584E02
B112586E02

INSPECTION PROCEDURE


1. INSPECT FUSE (AM2)

  1. Remove the AM2 fuse from the cowl side J/B RH.

  1. Measure the resistance of the fuse.

    Standard resistance:
    Below 1 Ω



 NG
REPLACE FUSE
OK


2. CHECK CONNECTORS

  1. Check that the connectors are securely connected and the terminals are not deformed or loose.

    OK:
    The connectors are securely connected and the terminals are not deformed or loose.



 NG
REPAIR OR REPLACE CONNECTORS
OK


3. CHECK WIRE HARNESS (POWER SOURCE CONTROL ECU - BATTERY AND BODY GROUND)

  1. B128304E19
    Disconnect the J55 ECU connector.

  1. Measure the voltage according to the value(s) in the table below.

    Standard voltage:
    Tester Connection (Symbols)
    		 Condition
    		 Specified Condition
    J55-33 (AM1) - Body ground
    		 Always
    		 10 to 14 V
    J55-12 (AM2) - Body ground
    		 Always
    		 10 to 14 V

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection (Symbols)
    		 Condition
    		 Specified Condition
    J55-6 (GND) - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4. CHECK FOR DTCS

  1. Delete the DTCs (Click here).

    HINT:
    After all the DTCs are cleared, check if the trouble occurs again 5 seconds after the engine switch is turned on (IG).

  1. Check for DTCs again.

    OK:
    No DTC is output.



 NG
GO TO DTC CHART
OK


5. READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

  1. Check the DATA LIST for proper functioning of the start switches 1 and 2.

    Power source control ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    St Sw 1
    		 Start Switch 1/ ON or OFF
    		 ON: Engine switch on (IG)
    OFF: Engine switch OFF
    		 -
    St Sw 2
    		 Start Switch 2/ ON or OFF
    		 ON: Engine switch on (IG)
    OFF: Engine switch OFF
    		 -

    OK:
    ON (engine switch on (IG)) and OFF (engine switch off) appear on the screen.



 NG
Go to step 10
OK


6. INSPECT RELAY (IG2)

  1. B060778E71
    Remove the IG2 relay from the engine room R/B No.2.

  1. Measure the resistance according to the value(s) in the table below.

    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 RELAY (IG2)
OK


7. INSPECT JUNCTION BLOCK (RH-IG RELAY, LH-IG RELAY, ACC RELAY, PWR POINT RELAY)

  1. RH-IG relay:B133435E01

    1. Disconnect the cowl side J/B RH connectors.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance:
      Tester Connection
      		 Condition
      		 Specified Condition
      RD-6 - RA-5 or RD-7
      		 Always
      		 136 to 250 Ω at 20°C (68°F)
      RD-6 - Body ground
      		 Always
      		 10 kΩ or higher
      RD-2 - RA-5 or RD-7
      		 Always
      		 68 to 250 Ω at 20°C (68°F)
      RD-2 - Body ground
      		 Always
      		 10 kΩ or higher
      RD-6 - RD-12
      		 Always
      		 Below 1 Ω
      RM-1 - RD-14
      		 When battery voltage is applied to terminals RD-6 and RA-5 or RD-7
      		 Below 1 Ω
      RM-1 - RD-27
      		 When battery voltage is applied to terminals RD-2 and RA-5 or RD-7
      		 Below 1 Ω
      RM-1 - RJ-16
      		 When battery voltage is applied to terminals RD-2 and RA-5 or RD-7
      		 Below 1 Ω

  1. LH-IG relay:B133436E01

    1. Disconnect the cowl side J/B LH connectors.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance:
      Tester Connection
      		 Condition
      		 Specified Condition
      LD-13 - LD-8 or LD-9
      		 Always
      		 68 to 250 Ω at 20°C (68°F)
      LD-13 - Body ground
      		 Always
      		 10 kΩ or higher
      LM-1 - LD-6
      		 When battery voltage is applied to terminals LD-13 and LD-8 or LD-9
      		 Below 1 Ω
      LM-1 - LD-29
      		 When battery voltage is applied to terminals LD-13 and LD-8 or LD-9
      		 Below 1 Ω



NG
REPLACE JUNCTION BLOCK
OK


8. CHECK WIRE HARNESS

  1. Inspect the resistance and voltage (Power source control ECU or battery - IG2 relay).B112479E01

    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance:
      Tester Connection (Symbols)
      		 Condition
      		 Specified Condition
      J55-35 (IG2D) - IG2 relay terminal 2
      		 Always
      		 Below 1 Ω
      IG2 relay terminal 1 - Body ground
      		 Always
      		 Below 1 Ω
      J55-35 (IG2D) or IG2 relay terminal 2 - Body ground
      		 Always
      		 10 kΩ or higher

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage:
      Tester Connection
      		 Condition
      		 Specified Condition
      IG2 relay terminal 5 - Body ground
      		 Always
      		 10 to 14 V

  1. Inspect the resistance and voltage (Power source control ECU or battery - Cowl side J/B RH).B133470E01

    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance:
      Tester Connection (Symbols)
      		 Condition
      		 Specified Condition
      J55-34 (IG1D) - RD-6
      		 Always
      		 Below 1 Ω
      J55-11 (ACCD) - RD-2
      		 Always
      		 Below 1 Ω
      RD-7 - Body ground
      		 Always
      		 Below 1 Ω
      RA-5 - Body ground
      		 Always
      		 Below 1 Ω
      J55-34 (IG1D) or RD-6 - Body ground
      		 Always
      		 10 kΩ or higher
      J55-11 (ACCD) or RD-2 - Body ground
      		 Always
      		 10 kΩ or higher

    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage:
      Tester Connection
      		 Condition
      		 Specified Condition
      RM-1 - Body ground
      		 Always
      		 10 to 14 V

  1. A118480E01
    Inspect the resistance (Cowl side J/B RH - Cowl side J/B LH).

    1. Measure the resistance according to the value(s) in the table below.

      Standard resistance:
      Tester Connection (Symbols)
      		 Condition
      		 Specified Condition
      RD-12 - LD-13
      		 Always
      		 Below 1 Ω
      LD-8 - Body ground
      		 Always
      		 Below 1 Ω
      LD-9 - Body ground
      		 Always
      		 Below 1 Ω

  1. B133471E01
    Inspect the voltage (Battery - Cowl side J/B LH).

    1. Measure the voltage according to the value(s) in the table below.

      Standard voltage:
      Tester Connection
      		 Condition
      		 Specified Condition
      LM-1 - Body ground
      		 Always
      		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


9. INSPECT POWER SOURCE CONTROL ECU

  1. B112480E09
    Reconnect the J55 ECU connector.

  1. Measure the voltage according to the value(s) in the table below.

    Standard voltage:
    Tester Connection (Symbols)
    		 Condition
    		 Specified Condition
    J55-34 (IG1D) - Body ground
    		 Engine switch off
    		 Below 1 V
    Engine switch on (IG)
    		 8 to 14 V
    J55-35 (IG2D) - Body ground
    		 Engine switch off
    		 Below 1 V
    Engine switch on (IG)
    		 8 to 14 V
    J55-11 (ACCD) - Body ground
    		 Engine switch off
    		 Below 1 V
    Engine switch on (ACC)
    		 8 to 14 V



NG
REPLACE POWER SOURCE CONTROL ECU
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (COWL SIDE J/B - EACH SYSTEM)

10. INSPECT ENGINE SWITCH

  1. Remove the engine switch.A109252E11

  1. Measure the resistance of the switch.

    Standard resistance:
    Tester Connection
    		 Switch Condition
    		 Specified Condition
    7 (SS1) - 5 (GND)
    		 Pushed
    		 Below 1 Ω
    2 (SS2) - 5 (GND)
    		 Pushed
    		 Below 1 Ω
    7 (SS1) - 5 (GND)
    		 Not pushed
    		 10 kΩ or higher
    2 (SS2) - 5 (GND)
    		 Not pushed
    		 10 kΩ or higher



NG
REPLACE ENGINE SWITCH
OK


11. CHECK WIRE HARNESS (POWER SOURCE CONTROL ECU AND BODY GROUND - ENGINE SWITCH)

  1. A109235E07
    Disconnect the J55 ECU connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection (Symbols)
    		 Condition
    		 Specified Condition
    J31-7 (SS1) - J55-14 (SSW1)
    		 Always
    		 Below 1 Ω
    J31-2 (SS2) - J55-37 (SSW2)
    		 Always
    		 Below 1 Ω
    J31-5 (GND) - Body ground
    		 Always
    		 Below 1 Ω
    J31-7 (SS1) or J55-14 (SSW1) - Body ground
    		 Always
    		 10 kΩ or higher
    J31-2 (SS2) or J55-37 (SSW2) - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE POWER SOURCE CONTROL ECU


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