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System Description [09/2014 - 11/2017]

  1. HEATED STEERING WHEEL SYSTEM 
    1. The heated steering wheel system heats the steering wheel assembly when the steering heater switch (refreshing seat switch) is operated.
    2. The heated steering wheel system uses a thermistor inside of the steering wheel assembly to detect the heater temperature and maintain the set temperature.
    3. The heated steering wheel timer function turns off the heater after a predetermined period of time.
  2. HEATER CONTROLLER SYSTEM 
    1. Operation description
      GTY452219Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      1. When the engine switch is on (IG), pressing the steering heater switch (refreshing seat switch) illuminates the LED and current is output from the steering wheel heater control assembly to the steering wheel heater unit of the heated steering wheel system. Pressing the steering heater switch (refreshing seat switch) again turns off the LED and stops the current from being output.
      2. A thermostat is installed in the steering wheel heater unit as a safety mechanism.
      3. The steering heater switch (refreshing seat switch) LED will go off when either of the following occurs: 1) an open or short in the steering wheel heater unit thermistor continues for 2 seconds or more; or 2) the steering heater switch (refreshing seat switch) is pressed continuously for 10 seconds or more.
      4. The timer will turn off the heater 30 minutes after the steering heater switch (refreshing seat switch) was first turned on.
    2. Signal input / output description
      GTY411836Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Signal Signal Name Function Signal Type
      Input Thermistor input Input of voltage corresponding to heater temperature Analog input
      Input Temperature setting input Input of voltage corresponding to temperature setting Analog input
      Input Operating switch input Input of power circuit latch operation estimate signal LOW / HI input
      Output LED output Output of LED LOW / HI input
      Output Heater output Output of heater LOW / HI input
      Output Latch output Power circuit maintenance LOW / HI input
    3. Safety function
      Content Operation
      When thermistor malfunction is detected Heater off
      When overheating (175°C (347°F)) of controller is detected Heater off
      When load short current (50 A or more) is detected Heater off
      When undervoltage (4.5 V) is detected Heater off
      OFF timer (30 min.) After preset time of timer passes, heater off
      Reverse voltage protection Protection circuit operates
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