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System Description

  1. PUSH-BUTTON START DESCRIPTION 
    1. The push-button start uses a push-type power switch, which the driver can operate by merely carrying the key. This system consists primarily of the main body ECU, power switch, ID code box, steering lock ECU, key, D-ACC relay, D-IG1 relay, ignition relay No. 2 (IG2) and certification ECU. The main body ECU controls the system. This function operates in cooperation with the smart access system with push-button start. The table below shows the transition of the power 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 and shift lever conditions.
      POWER SOURCE MODE PATTERN

      Condition Power Source Mode Pattern
      Brake pedal not depressed, shift lever in P Each time power switch is pushed
      OFF → ON (ACC) → ON (IG) → OFF
      Brake pedal not depressed When power switch is pushed in ON (READY) condition
      ON (READY) → OFF
      Brake pedal depressed, shift lever in P When power switch is pushed once
      OFF → ON (READY)
      Brake pedal depressed, shift lever in P When power switch is pushed in ON (ACC) condition
      ON (ACC) → ON (READY)
      Brake pedal depressed, shift lever in P When power switch is pushed in ON (IG) condition
      ON (IG) → ON (READY)
      Brake pedal depressed When power switch is pushed in ON (READY) condition
      ON (READY) → OFF

      When the battery of the key or card key is low, the push-button start function can be operated by touching the key or card key to the power switch.

  2. FUNCTION OF COMPONENT 
    FUNCTION OF COMPONENT

    Components Function
    Power Switch (Transponder Key Amplifier)
    • Transmits power switch signal to main body ECU
    • Informs driver of power source mode or system abnormality with indicator light illumination
    • Receives ID code and transmits it to certification ECU when key or card key battery is low or affected by wave noise, etc
    Key Receives signals from oscillators and returns ID code to entry door control receiver
    Indoor Key Oscillator Receives request signal from certification ECU and forms detection area in vehicle interior
    Door Control Receiver Receives ID code from key and transmits it to certification ECU
    Main Body ECU
    • Changes power source mode in 4 stages (OFF, ON (ACC), ON (IG), ON (READY)) in accordance with state of shift lever position sensor
    • Controls push-button start function in accordance with signals received from switches and each ECU
    Certification ECU Certifies ID code received from entry door control receiver and transmits certification results to ID code box and steering lock ECU
    Shift Lock Control ECU Outputs state of shift position to main body ECU
    Stop Light Switch Outputs state of brake pedal to main body ECU.
    ID Code Box Receives steering unlock or engine immobilizer unset signals from certification ECU, certifies them, and transmits each unset signal to steering lock ECU or hybrid vehicle control ECU
    Hybrid Vehicle Control ECU Receives signal from ID code box and main body ECU and starts hybrid control system
  3. SYSTEM FUNCTION 

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

    FUNCTION CHART

    Control Outline
    Power Switch Control
    • When driver operates power switch with key in driver's possession, certification ECU starts indoor key oscillator, which transmits request signal to key Upon receiving this signal, key transmits
    • ID code signal to door control receiver ID code box verifies check results received from certification ECU via LIN line and sends them to main body ECU Based on these results, main body ECU authorizes operation of power switch
    Diagnosis When main body ECU detects malfunction, main body ECU diagnoses and memorizes failed section
  4. CONSTRUCTION AND OPERATION 
    1. Power switch

      The power switch consists of a momentary type switch, 3 color (amber, green, greenish white) LEDs, and transponder key amplifier

      • The greenish white LED is for illumination.
      • The amber and green LEDs are for the indicator light. The driver can check the present power source mode and whether the hybrid control system can start or not by the illumination state of the indicator light.
      • When the main body ECU detects an abnormality in the smart access system with push-button start, it makes the amber indicator light flash. If the hybrid control system is stopped in this state, it might not be possible to restart it.
        Fig 1: Identifying Power Switch
        G05780651Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Indicator light condition.

      Power switch indicator light condition 

      POWER SWITCH INDICATOR LIGHT CONDITION

      Power Source Mode/Condition Indicator Light Condition
      Brake pedal released Brake pedal depressed, shift lever in P
      OFF OFF Illuminates (green)
      ON (ACC, IG) Illuminates (amber) Illuminates (green)
      ON (READY) OFF OFF
      Steering lock not unlocked Flashes (green) for 30 seconds Flashes (green) for 30 seconds
      System malfunction Flashes (amber) for 15 seconds Flashes (amber) for 15 seconds
      Stop light switch malfunction with shift lever in P Flashes (green) for 15 seconds Flashes (green) for 15 seconds
    3. Main body ECU:

      The main body ECU consists of the D-IG1 relay, D-ACC relay and ignition relay No. 2 (IG2) actuation circuits and CPU.

  5. SYSTEM NOT OPERATING NORMALLY (DUE TO KEY BATTERY DEPLETION, ELECTRICAL NOISE, ETC.) 
    1. To operate the push-button start function when the key or card key battery is low or affected by wave noise, etc., touch the LEXUS mark of the key or card key to the power switch while depressing the brake pedal with the shift lever in P.
    2. The main body 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 door control receiver, so it actuates the transponder key amplifier built into the power switch
    4. The transponder key amplifier outputs an engine immobilizer radio wave to the key
      Fig 2: Touching LEXUS Mark Of Key Or Card Key To Power Switch
      G05780652Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    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 main body ECU. The buzzer in the combination meter sounds at the same time
    8. After the buzzer sounds, with the shift lever in P, if the power switch is pressed within 10 seconds with the brake pedal not depressed, the power source mode changes to ON (ACC) or ON (IG), as in the normal condition.
  6. DIAGNOSIS 

    The main body 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 power switch flashes to warn the driver At the same time, the ECU stores the 5-digit DTC (Diagnostic Trouble Code) in memory.

    • The indicator light warning continues for 15 seconds even after the power source mode is changed to OFF.
    • The DTC can be read by connecting the intelligent tester or Techstream to the DLC3.
    • The push-button start function cannot be operated if a malfunction occurs.
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