Lexus IS250 · Service Manual ENGINE

Power Mode does not Change to ON (IG)

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

B112577E04
B133472E01

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 (GND2) - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4. INSPECT RELAY (IG1 RELAY)

  1. B060778E73
    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
Go to step 8
OK


5. INSPECT JUNCTION BLOCK (RH-IG RELAY, LH-IG RELAY)

  1. RH-IG relay:B133435E02

    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 - RD-12
      		 Always
      		 Below 1 Ω
      RD-6 - Body ground
      		 Always
      		 10 kΩ or higher
      RM-1 - RD-14
      		 When battery voltage is applied to terminals RD-6 and RD-12 or RA-5 or RD-7)
      		 Below 1 Ω

  1. LH-IG relay:B133436E02

    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 andLD-8 or LD-9)
      		 Below 1 Ω
      LM-1 - LD-29
      		 When battery voltage is applied to terminals LD-13 andLD-8 or LD-9)
      		 Below 1 Ω



NG
Go to step 8
OK


6. 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).B133470E02

    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
      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

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

      Standard voltage:
      Tester Connection (Symbols)
      		 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-3
      		 Always
      		 Below 1 Ω
      RD-12 - Body ground
      		 Always
      		 10 kΩ or higher
      LD-18 - Body ground
      		 Always
      		 Below 1 Ω
      LD-9 - Body ground
      		 Always
      		 Below 1 Ω

  1. B133471E02
    Inspect the voltage (Battery - Cowl side J/B LH).Measure the voltage according to the value(s) in the table below.

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



NG
Go to step 9
OK


7. INSPECT POWER SOURCE CONTROL ECU

  1. B112480E10
    Reconnect the connectors.

  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



NG
REPLACE POWER SOURCE CONTROL ECU
OK

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

8. REPLACE FAULTY RELAY OR J/B AND CHECK POWER SOURCE CONTROL ECU

  1. B112480E10
    Replace a faulty relay or J/B and then connect the power source control 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



NG
REPLACE POWER SOURCE CONTROL ECU
OK

END

9. REPLACE FAULTY WIRE HARNESS OR CONNECTOR AND CHECK POWER SOURCE CONTROL ECU

  1. B112480E10
    Repair or replace a faulty wire harness or connector and then connect the power source control 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



NG
REPLACE POWER SOURCE CONTROL ECU
OK

END


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