Entry And Start System System Description

Engine. Lexus Gs430, Gs300. Uzs190 Grs190
3Uz-Fe Starting. Lexus Gs430, Gs300. Uzs190 Grs190

  1. PUSH-BUTTON START 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 DESCRIPTION

  1. The push-button start uses a push-type engine switch, which the driver can operate by merely carrying the key. This system consists primarily of the power source control ECU, engine switch, ID code box, steering lock ECU, key, ACC relay, IG1 relay, IG2 relay and certification ECU. The power source control ECU controls the system. This function operates in cooperation with the entry and start system. The table below shows the transition of the engine switch, which depends on whether the brake pedal is depressed or released.

  2. 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 engine switch is pushed once
    1. off → engine start
    Not depressed
    		P position
    		Each time engine switch is pushed
    1. off → on (ACC) → on (IG) → off
    Except P position
    		Each time engine switch is pushed
    1. off → on (ACC) → on (IG) → on (ACC)
    -
    		P position
    		When engine switch is pushed in the on (IG) condition
    1. on (IG) → off
    -
    		Except P position
    		When engine switch is pushed in the on (IG) condition
    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.

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 power source mode or system abnormality with illumination stage of indicator light.
  3. Receives ID code and transmits it to certification ECU when battery of key is low.
Key
Receives signals from oscillators and returns ID code to entry door control receiver.
Indoor Electrical Key Oscillator
  1. Front and Rear
Receives request signal from certification ECU and forms detection area in vehicle interior.
Entry Door Control Receiver
Receives ID code from key and transmits it to 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 and state of stop light switch.
  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 immobiliser 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 immobiliser 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 key in driver's possession, certification ECU starts indoor electrical key oscillator, which transmits request signal to key. Upon receiving this signal, key transmits ID code signal to power source control ECU.
  2. ID code box verifies check results received from 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, power source control ECU diagnoses and memorizes failed section.

CONSTRUCTION AND OPERATION
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Starting.Starting System.Entry And Start System System Description

  1. Engine Switch
    Engine switch consists of a momentary type switch, 3 color (amber, green, greenish white) LEDs, and 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 or not 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 system, it makes the amber indicator light flash. If the engine stopped in this state, it might 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
    		Brake pedal depressed, shift lever in P or N
    off
    		OFF
    		Illuminates ON (Green)
    on (ACC, IG)
    		Illuminates ON (Amber)
    		Illuminates ON (Green)
    Engine running
    		OFF
    		OFF
    Steering lock locked
    		Flashes (Green) for 30 sec.
    		Flashes (Green) for 30 sec.
    System malfunction
    		Flashes (Amber) for 15 sec.
    		Flashes (Amber) for 15 sec.


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

    1. The hold circuit is installed to prevent the power supply to the relays from being cut off when an abnormality occurs in the IG1 and/or IG2 relay actuation circuits during driving.

    Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe Starting.Starting System.Entry And Start System System Description

    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 to 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
This system has different power source mode patterns depending on the brake pedal condition and shift lever position.
When the battery of the key is low, the push-button start function can be operated by holding the key against the engine switch.

Brake Pedal
Shift Lever
Power Source Mode Pattern
Depressed
P or N position
When engine switch is pushed once
  1. off → engine start
Not depressed
P position
Each time engine switch is pushed
  1. off → on (ACC) → on (IG) → off
Except P position
Each time engine switch is pushed
  1. off → on (ACC) → on (IG) → on (ACC)
-
P position
When engine switch is pushed in the on (IG) condition
  1. on (IG) → off
-
Except P position
When engine switch is pushed in the on (IG) condition
  1. on (IG) → on (ACC)
  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 Gs430, Gs300. Uzs190 Grs190.3Uz-Fe 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).

WHEN KEY BATTERY IS LOW
Lexus Gs430, Gs300. Uzs190 Grs190.3Uz-Fe 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.

  2. The power source control ECU transmits a key verification request signal from the stop light switch 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, 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 the 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.