Lexus IS250 · Service Manual ENGINE

Engine does not Start

Circuit diagnosis

DESCRIPTION


ENGINE START SYSTEM OPERATION

  1. A/T Models: If the engine switch is pressed with the shift lever in P or N and the brake pedal depressed, the power source control ECU determines that it is an engine start request.

  2. M/T Models: If the engine switch is pressed with the clutch pedal depressed, the power source control ECU determines that it is an engine start request.

  3. The certification ECU and other ECUs perform key verification via the LIN communication line.

  4. The power source control ECU activates the ACC relay.

  5. The power source control ECU activates the IG1 and IG2 relays. The engine switch indicator light turns green.

  6. The certification ECU outputs a steering UNLOCK signal. The signal is sent to the steering lock ECU via the power source control ECU.

  7. The power source control ECU sends an engine start request signal to the ECM.

  8. The ECM sends an ACC cut request signal to the power source control ECU.

  9. The ECM and power source control ECU activate the ST relay.

  10. The power source control ECU deactivates the ACC relay until the ECU detects an engine start.

  11. When engine revolution speed reaches 200 rpm, the power source control ECU determines that the engine has been started.
    The ECU reactivates the ACC relay and turns off the engine switch indicator light.

    Symbols of power source control ECU
    		 Signals
    STP
    		 Stop light switch ON signal
    SSW1/SSW2
    		 Engine switch ON signal
    ACCD
    		 ACC relay operation signal
    IG2D
    		 IG2 relay operation signal
    STR2
    		 ST relay operation signal
    STR1
    		 Park/neutral position switch signal (A/T), Clutch start switch (M/T)
    TACH
    		 Engine start detection signal
    STSW
    		 Starter activation request signal
    CTSW
    		 ACC cut request signal

A109230E06

WIRING DIAGRAM

See CRANKING HOLDING FUNCTION CIRCUIT (Click here).

INSPECTION PROCEDURE


1. CHECK IF ENGINE START (INITIALIZE STEERING LOCK)

  1. Shift lever is P position.

  1. Open and close the driver's door with the engine switch off. Check if the engine can be started.

    OK:
    Engine can be started.

    HINT:
    After the battery is discharged and then recharged, the engine may not start unless the steering lock is initialized using the above procedure.



 OK
END
NG


2. CHECK FOR DTC

  1. Delete the DTCs (Click here).

  1. Check for DTCs again.

    OK:
    No DTC is output.



 NG
GO TO DTC CHART
OK


3. CHECK SWITCH CONDITION

  1. Check the engine start function.

    1. A/T Models: When the key is inside the vehicle and the shift lever is in P, check that pressing the engine switch causes the power source mode to change as follows.

    2. M/T Models: When the key is inside the vehicle, check the brake pedal causes the engine to start.

      OK:
      Engine starts.

      HINT:
      1. If power mode does not change to ON (IG and ACC) (Click here).
      2. If power mode does not change to ON (IG) (Click here).
      3. If power mode does not change to ON (ACC) (Click here).



 NG
PROCEED TO APPROPRIATE PROBLEM SYMPTOMS SHOWN IN PROBLEM SYMPTOMS TABLE
OK


4. CHECK BASIC FUNCTION

  1. Check the engine cranking function.

    1. A/T Models: When there is fuel in the fuel tank, the key is inside the vehicle and the shift lever is in P, check that depressing the brake pedal and pressing the engine switch cranks the engine.

    2. M/T Models: When there is fuel in the tank, the key is inside the vehicle, check that depressing the clutch pedal and the brake pedal and pressing the engine switch cranks the engine.

      OK:
      Engine cranks.



 NG
Go to step 18
OK


5. READ VALUE OF INTELLIGENT TESTER (STA SIGNAL)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

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

    Standard: 
    Engine Swithc Position
    		 ON (IG)
    		 ENGINE START
    Started Sig
    		 OFF
    		 ON

    OK:
    ON (brake pedal depressed) and OFF (brake pedal released) appear on the screen.



 OK
Go to step 12
NG


6. READ VALUE OF INTELLIGENT TESTER (STOP LIGHT SWITCH)

  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 stop light switch.

    Power source control ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    Stop Lamp SW1
    		 Stop light Switch 1/ ON or OFF
    		 ON: Brake pedal depressed
    OFF: Brake pedal released
    		 -

    OK:
    ON (brake pedal depressed) and OFF (brake pedal released) appear on the screen.

    HINT:
    If the result of the inspection for a tester display is not as specified, perform troubleshooting for DTC B2284 first (Click here).



 NG
GO TO DTC CHART
OK


7. READ VALUE OF INTELLIGENT TESTER (STEERING LOCK)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

    Power source control ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    Str Unlock SW
    		 Steering lock condition/ ON or OFF
    		 ON: Steering is unlocked
    OFF: Steering is locked
    		 -

    OK:
    ON (steering is unlocked) and OFF (steering is locked) appear on the screen.



 NG
Go to step 22
OK


8. CHECK STEERING LOCK

  1. Check if the steering lock is released when turning the engine switch on (ACC).

    OK:
    The steering lock is released.



 NG
GO TO STEERING LOCK SYSTEM
OK


9. INSPECT ECM (STAR AND STSW VOLTAGE)

  1. A124678E19
    Measure the voltage of the A5 and E4 ECM connectors while cranking the engine.

    Standard voltage:
    Tester Connection
    		 Specified Condition
    STAR (E4-4) - E1 (E4-7)
    		 9 to 14 V
    STSW (A5-19) - E1 (E4-7)
    		 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 16
A


10. INSPECT RELAY (ST CUT)

  1. B016200E23
    Remove the ST CUT relay from the engine room J/B and R/B No. 2.

  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 RELAY
OK


11. INSPECT PARK/NEUTRAL POSITION SWITCH (A/T) OR CLUTCH START SWITCH (M/T)

  1. A117846E02
    Disconnect the park/neutral position (PNP) switch (A/T) or clutch switch (M/T) connector.

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

    Standard resistance (A/T):
    Shift Position
    		 Tester Connection
    		 Specified Condition
    P
    		 4 - 5
    		 Below 1 Ω
    N
    		 4 - 5
    		 Below 1 Ω
    Except N or P
    		 4 - 5
    		 10 kΩ or higher

    Standard resistance (M/T):
    Clutch Pedal Operation
    		 Tester Connection
    		 Specified Condition
    Depressed
    		 1 - 2
    		 Below 1 Ω
    Released
    		 1 - 2
    		 10 kΩ or higher



NG
REPLACE PNP SWITCH (A/T) OR CLUTCH START SWITCH (M/T)
OK

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

12. INSPECT RELAY (STARTER)

  1. B016200E23
    Remove the starter relay from the engine room J/B and R/B No. 1.

  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 RELAY
OK


13. CHECK HARNESS AND CONNECTOR (PNP SWITCH (A/T) OR CLUTCH START SWITCH (M/T) - ST RELAY)

  1. A117847E06
    Check the harness and the connectors between the park/neutral position switch and the starter relay.

    1. Disconnect the E45*1, A24*2 switch connector.*1: A/T*2: M/T

    2. Remove the starter relay from the engine room J/B and R/B No. 1.

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

      Standard resistance (A/T) (Check for open):
      Tester Connection
      		 Specified Condition
      Park/Neutral position switch (E45-5) - Starter relay (1)
      		 Below 1 Ω

      Standard resistance (M/T) (Check for open):
      Tester Connection
      		 Specified Condition
      Clutch start switch (A24-2) - Starter relay (1)
      		 Below 1 Ω

      Standard resistance (A/T) (Check for short):
      Tester Connection
      		 Specified Condition
      Park/Neutral position switch (E45-5) or Starter relay (1) - Body ground
      		 10 kΩ or higher

      Standard resistance (M/T) (Check for short):
      Tester Connection
      		 Specified Condition
      Clutch start switch (A24-2) or Starter relay (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 J/B and R/B No. 1.

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

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



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


14. INSPECT ENGINE ROOM RELAY BLOCK (STARTER RELAY VOLTAGE)

  1. A109886E03
    Remove the starter relay from the engine room J/B and R/B No. 1.

  1. Measure the voltage of the engine room J/B and R/B No. 1 and the body ground.

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



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


15. INSPECT STARTER ASSEMBLY

HINT:
Click here



NG
REPAIR OR REPLACE STARTER ASSEMBLY
OK

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

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

  1. A107718E09
    Check the harness and the connectors between the power source control ECU and ECM.

    1. Disconnect the power source control ECU connector.

    2. Disconnect the A5 ECM connector.

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

      Standard resistance (Check for open):
      Tester Connection
      		 Specified Condition
      J55-39 (STSW) - A5-19 (STSW)
      		 Below 1 Ω

      Standard resistance (Check for short):
      Tester Connection
      		 Specified Condition
      J55-39 (STSW) or A5-19 (STSW) - Body ground
      		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


17. CHECK AND REPLACE POWER SOURCE CONTROL ECU

  1. Replace the power source control ECU.

  1. Check the engine cranking function.

    1. A/T Models: When there is fuel in the fuel tank, the key is inside the vehicle and the shift lever is in P, check that depressing the brake pedal and pressing the engine switch cranks the engine.

    2. M/T Models: When there is fuel in the tank, the key is inside the vehicle, check that depressing the clutch pedal and the brake pedal and pressing the engine switch cranks the engine.

      OK:
      Engine cranks.

      HINT:
      After the replaced power source control ECU, the engine may not start unless the each system are initialized using the above procedure.



 NG
REPLACE ECM
OK

END

18. READ VALUE OF INTELLIGENT TESTER (L CODE)

  1. Reconnect the connectors.

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

    Certification ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    L Code Chk
    		 L code check/ ON or NG
    		 OK: Normal
    NG: Malfunction
    		 Electrical key in the cabin

    OK:
    OK is displayed on the screen.

    HINT:
    If the result of the inspection for a tester display is not as specified, there may be malfunction of the steering lock ECU or the ID code box.



 NG
GO TO ENGINE IMMOBILISER SYSTEM
OK


19. READ VALUE OF INTELLIGENT TESTER (ENGINE START REQUEST)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

    Certification ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    Start Rqst
    		 Start request signal response/ OK or NG
    		 OK: Received
    NG: Non-received
    		 -

    OK:
    OK (received) and NG (non-received) appear on the screen.



 NG
REPLACE CERTIFICATION ECU
OK


20. READ VALUE OF INTELLIGENT TESTER (S CODE)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the engine switch on (IG).

    Certification ECU: 
    Item
    		 Measurement Item/Display (Range)
    		 Normal Condition
    		 Diagnostic Note
    S Code Chk
    		 S code check/ OK or NG
    		 OK: Normal
    NG: Malfunction
    		 -

    OK:
    OK is displayed on the screen.

    HINT:
    If the result of the inspection for a tester display is not as specified, there may be malfunction of the certification ECU or the ID code box.



 NG
GO TO ENGINE IMMOBILISER SYSTEM
OK


21. INSPECT ID CODE BOX

  1. B120812E01
    Check the input signal waveform.

    1. Connect the oscilloscope to the terminals J69-6 (EFIO) and A6-6 (IMI).

    2. Turn the engine switch on (IG).

    3. Check the signal waveform according to the condition(s) in the table below.

      Item
      		 Condition
      Tool setting
      		 10 V/DIV., 100 ms./DIV.
      Vehicle condition
      		 Engine switch on (IG)



NG
REPLACE ID CODE BOX
OK

END

22. CHECK WIRE HARNESS (POWER SOURCE CONTROL ECU - STEERING LOCK ECU)

  1. A118197E01
    Disconnect the ECU connector.

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

    Standard resistance:
    Tester Connection (Symbols)
    		 Specified Condition
    J55-26 (SLP) - J29-4 (SLP1)
    		 Below 1 Ω
    J55-26 (SLP) or J29-4 (SLP1) - Body ground
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


23. INSPECT POWER SOURCE CONTROL ECU

  1. B112480E16
    Reconnect the J55 ECU connector.

  1. A130277E02
    Connect the oscilloscope to the power source control ECU terminals specified in the table below and check the waveform.
    Item
    		 Contents
    Terminal (Symbols)
    		 J55-26 (SLP) - Body ground
    Equipment Setting
    		 2 V/DIV, 100 ms/DIV
    Condition
    		 Engine switch on (IG)

    OK:
    The waveform appears as shown in the illustration.

    HINT:
    The waveform varies depending on the contents of communication.



 NG
REPLACE POWER SOURCE CONTROL ECU
OK


24. INSPECT STEERING LOCK ECU

  1. B112480E16
    Reconnect the J29 ECU connector.

  1. A130277E01
    Connect the oscilloscope to the power source control ECU terminals specified in the table below and check the waveform.
    Item
    		 Contents
    Terminal (Symbols)
    		 J55-26 (SLP) - Body ground
    Equipment Setting
    		 2 V/DIV, 100 ms/DIV
    Condition
    		 Steering is LOCK / UNLOCK

    OK:
    The waveform appears as shown in the illustration.

    HINT:
    The waveform varies depending on the contents of communication.



 NG
REPLACE STEERING LOCK ECU
OK

REPLACE POWER SOURCE CONTROL ECU


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