Entry And Start System System Description

Engine. Lexus Is250, Is220D. Gse20 Ale20
4Gr-Fse Starting. Lexus Is250, Is220D. Gse20 Ale20

  1. PUSH-BUTTON START FUNCTION DESCRIPTION

  1. FUNCTION OF COMPONENT

  1. SYSTEM FUNCTION

  1. CONSTRUCTION AND OPERATION

  1. PUSH-BUTTON START FUNCTION OPERATION

  1. WHEN KEY BATTERY IS LOW

  1. DIAGNOSIS

Entry And Start System -- System Description



PUSH-BUTTON START FUNCTION DESCRIPTION

  1. The push-button start function uses a push-type engine switch, which the driver can operate by merely carrying the electrical key. This system consists primarily of the power source control ECU, engine switch, ID code box, steering lock ECU, electrical key, ACC relay, IG1 relay, IG2 relay and certification ECU. The power source control ECU controls the function. This function operates in cooperation with the entry and start system.


FUNCTION OF COMPONENT

Components
Function
Engine Switch
  1. Transponder Key Amplifier
  1. Transmits engine switch signal to power source control ECU.
  2. Informs driver of a power source mode or system abnormality with illumination stage of indicator light.
  3. Receives ID code and transmits it to certification ECU when the key battery is low.
Electrical Key
Receives signals from oscillators and returns ID code to entry door control receiver.
Electrical Key Oscillator
  1. Console and Rear Seat
Receives request signals from certification ECU and forms detection area in vehicle interior.
Entry Door Control Receiver
Receives ID code from electrical key and transmits it to the certification ECU.
Power Source Control ECU
  1. Changes power source mode in 4 stages (off, on (ACC), on (IG), start) in accordance with shift position (A/T) and state of stop light switch (A/T), clutch start switch (M/T) and key ID matches vehicle.
  2. Controls push-button start function in accordance with signals received from switches and each ECU.
Certification ECU
Certifies the ID code received from entry door control receiver and transmits certification results to the ID code ECU and steering lock ECU.
Stop Light Switch
Outputs state of brake pedal to power source control ECU.
ID Code Box
Receives steering unlock or engine immobiliser unset signals from certification ECU, certifies them, and transmits each unset signal to steering lock ECU or ECM.
ECM
  1. Receives engine start request signal from power source control ECU, turns ON ST relay, and starts engine.
  2. Receives signal from ID code ECU and performs engine ignition and injection.

SYSTEM FUNCTION
The electric controls of the push-button start function are described below:

Control
Outline
Engine switch control
  1. When driver operates engine switch with electrical key in driver's possession, certification ECU starts indoor electrical key oscillator, which transmits request signal to electrical key. Upon receiving this signal, the electrical key transmits ID code signal to power source control ECU.
  2. ID code box verifies check results received from the certification ECU via LIN and sends them to power source control ECU. Based on these results, power source control ECU authorizes operation of engine switch.
Diagnosis
When power source control ECU detects malfunction, the power source control ECU diagnoses and memorizes the failed section.

CONSTRUCTION AND OPERATION
Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Starting.Starting System.Entry And Start System System Description

  1. Engine Switch
    The engine switch consists of a momentary type switch, 3 color (amber, green, greenish white) LEDs, and a transponder key amplifier.

    1. The greenish white LED is for illumination.
    2. The amber and green LEDs are for the indicator lights. The driver can check the present power source mode and whether the engine can start in accordance with the illumination state of the indicator light.
    3. When the power source control ECU detects an abnormality in the push-button start function, it makes the amber indicator light flash. If the engine stopped in this state, it may not be possible to restart it.

  2. Indicator Light Condition

    Engine switch indicator light condition:
    Power Source Mode/Condition
    		Indicator Light Condition
    Brake pedal released (A/T)
    Clutch pedal released (M/T)
    		Brake pedal depressed, shift lever in P or N (A/T)
    		Clutch pedal depressed (M/T)
    off
    		OFF
    		Turns ON (Green)
    (Key ID matches vehicle)
    		Turns ON (Green)
    (Key ID matches vehicle)
    on (ACC, IG)
    		Turns ON (Amber)
    		Turns ON (Green)
    		Turns ON (Green)
    Engine running
    		OFF
    		OFF
    		OFF
    Steering lock not unlocked
    		Flashes (Green) for 30 sec.
    		Flashes (Green) for 30 sec.
    		Flashes (Green) for 30 sec.
    System malfunction
    		Flashes (Amber) for 15 sec.
    		Flashes (Amber) for 15 sec.
    		Flashes (Amber) for 15 sec.
    Clutch start switch malfunction (M/T)
    		Flashes (Green) for 15 sec.
    		Flashes (Green) for 15 sec.
    		Flashes (Green) for 15 sec.

  3. Power Source Control ECU
    The power Source Control ECU consists of the ACC, IG1 and IG2 relay actuation circuits and CPU.

    HINT:
    Before removing the battery, make sure to turn the engine switch off. The power source control ECU constantly stores the present power source mode in its memory. Therefore, if the power source control ECU is interrupted by disconnecting the battery, the power source control ECU restores the power source mode after the battery is reconnected. For this reason, if the battery is disconnected when the engine switch is other than off, the power will be restored to the vehicle at the same time the power is restored to the power source control ECU (by reconnecting the battery).

PUSH-BUTTON START FUNCTION OPERATION

  1. A/T Models: This system has different power source mode patterns depending on the brake pedal condition and shift lever position.

    Brake Pedal
    		Shift Lever
    		Power Source Mode Pattern
    Depressed
    		P or N position
    		When the engine switch is pushed once.
    1. off → engine start
    2. on (ACC) → engine start
    3. on (IG) → engine start
    Not depressed
    		P position
    		Each time the engine switch is pushed.
    1. off → on (ACC) → on (IG) → off
    Except P position
    		Each time the engine switch is pushed.
    1. off → on (ACC) → on (IG) → on (ACC)
    -
    		P position
    		When the engine switch is pushed in the on (IG) condition (engine running).
    1. on (IG) → off
    -
    		Except P position
    		When the engine switch is pushed in the on (IG) condition (engine running).
    1. on (IG) → on (ACC)
    When the battery of the key is low, the push-button start function can be operated by holding the key against the engine switch.
    1. After approximately 1 hour has passed with the engine switch on (ACC) and the shift position in P, the power source control ECU will automatically cut the power supply (the power source mode changes to off).

    2. The illustration below shows the transition of power source modes.
      Transition of power source mode:


      Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Starting.Starting System.Entry And Start System System Description

      HINT:
      While the vehicle is being driven normally, operation of the engine switch is disabled. However, if the engine must be stopped in an emergency while the vehicle is being driven, pressing the engine switch for 3 seconds or more stops the engine. Power source mode changes from start to on (ACC).


  2. M/T Models: Start function has different power source patterns to suit the clutch pedal condition.

    Clutch Pedal
    		Power Source Mode Pattern
    Depressed
    		When the engine switch is pushed once.
    1. off → engine start
    2. on (ACC) → engine start
    3. on (IG) → engine start
    Not depressed
    		Each time the engine switch is pushed.
    1. off → on (ACC) → on (IG) → off
    -
    		When the engine switch is pushed in the on (IG) condition (engine running).
    1. on (IG) → off
    When the battery of the key is low, the push-button start function can be operated by holding the key against the engine switch.
    1. After approximately 1 hour has passed with the engine switch on (ACC) and the power source control ECU will automatically cut the power supply (the power source mode changes to off).
    2. The illustration below shows the transition of power source modes.
    Transition of power source mode M/T:

    Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Starting.Starting System.Entry And Start System System Description

    HINT:
    While the vehicle is being driven normally, operation of the engine switch is disabled. However, if the engine must be stopped in an emergency while the vehicle is being driven, pressing the engine switch for 3 seconds or more stops the engine. Power source mode changes from engine start to on (ACC).

WHEN KEY BATTERY IS LOW
Lexus Is250, Is220D. Gse20 Ale20.4Gr-Fse Starting.Starting System.Entry And Start System System Description

  1. To operate the push-button start function when the key battery is low, hold the key close to the engine switch with the brake pedal depressed (A/T) or clutch pedal depressed (M/T).

  2. The power source control ECU transmits a key verification request signal to the certification ECU.

  3. The certification ECU does not receive an ID code response from the entry door control receiver, so it actuates the transponder key amplifier built into the engine switch.

  4. The transponder key amplifier outputs an engine immobiliser radio wave to the key.

  5. The key receives the radio wave, and returns a radio wave response to the transponder key amplifier.

  6. The transponder key amplifier combines the key ID codes with the radio wave response, and transmits it to the certification ECU.

  7. The certification ECU judges and verifies the ID code, and transmits a key verification OK signal to the power source control ECU. The buzzer in the combination meter sounds at the same time.

  8. After the buzzer sounds, if the engine switch is pressed within 5 seconds with the brake pedal not depressed (A/T) or clutch pedal not depressed (M/T), the power source mode changes to on (ACC) or on (IG), the same as in the normal condition.


DIAGNOSIS
The power source control ECU can detect malfunctions in the push-button start function when the power source mode is on (IG).
When the ECU detects a malfunction, the amber indicator light of the engine switch flashes to warn the driver. At the same time, the ECU stores a 5-digit DTC (Diagnostic Trouble Code) in the memory.
  1. The indicator light warning continues for 15 seconds even after the power source mode is changed to off.
  2. The DTC can be read by connecting the intelligent tester to the DLC3.
  3. The push-button start function cannot be operated if a malfunction occurs.