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Home >> Scion >> 2012 >> iQ >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> CVT Transaxle (Diagnostics - Introduction) >> Continuously Variable Transaxle System >> Fail-Safe Chart >> Fail-Safe Chart

Fail-Safe Chart

  1. Description 

    This function minimizes the loss of the Continuously Variable Transaxle (CVT) system functions when a malfunction occurs in a sensor or solenoid.

  2. Fail-safe 
    1. Fail-safe control list:
      Malfunction Part Function
      Transmission revolution sensor (NIN) The ECM calculates the input shaft speed based on a signal from the turbine speed sensor to perform normal control.
      Transmission revolution sensor (NOUT) The ECM calculates the output shaft speed based on a signal from the speed sensor to perform normal control.
      Transmission revolution sensor (NT) The ECM calculates the turbine speed based on a signal from the primary pulley speed sensor to perform normal control.
      Shift control solenoid valve DS1 The ECM stops current to the solenoid. The gear ratio will be adjusted to a lower ratio compared to the normal ratio.
      Shift control solenoid valve DS2 The ECM stops current to the solenoid. The gear ratio will be adjusted to the highest ratio.
      Lock-up solenoid SL The ECM stops current to the solenoid to cancel the lock up. The ECM also uses solenoid SL to cancel forward clutch pressure control to hydraulically perform forward clutch pressure control.
      Lock-up engagement solenoid DSU The ECM stops current to the solenoid to completely cancel the lock up.
      Belt clamping pressure linear solenoid SLS The ECM stops current to the solenoid to maximize the secondary oil pressure in order to set the gear ratio to a predetermined value. The ECM also uses solenoid SLS to cancel forward clutch pressure control to hydraulically perform forward clutch pressure control.
      CVT fluid temperature sensor The ECM sets the fluid temperature to a predetermined value to perform normal control.
      Yaw rate and acceleration sensor
      (G sensor)
      The ECM cancels neutral control when a DTC is stored.