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Fail-Safe Chart

WARNING: This page is about a different car, the 2010 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.
  1. FAIL-SAFE FUNCTION 
    1. When communication fails in any of the main wires (communication lines) due to a short circuit or other causes, the fail-safe function, which is specified for each system, operates to prevent the system from malfunctioning.
    2. The table below shows the effects on each system when communication is impossible. For further details, refer to each system.
      Function
      1. Control Master ECU
      2. Related ECU
      		 Behavior when Communication not Possible DTC Detection (Recognition by Driver) DTC (Communication Interruption Mode)
      TC DTC output (Sends DTCs to the combination meter ECU while receiving a signal from the ECM indicating TC is on.)
      1. Center airbag sensor assembly
      2. ECM, Combination meter assembly (combination meter ECU)
      		 TC service function stops Not possible (Recognition by driver not possible) -
      Event Data Recorder (EDR) (Records conditions, such as vehicle speed, amount accelerator is depressed, and shift lever position when the event data recorder recording conditions are met.)
      1. Center airbag sensor assembly
      2. ECM, Combination meter assembly (combination meter ECU)
      		 Invalid value is stored in EDR Not possible (Recognition by driver not possible) -
      SRS warning light control (Turns the warning light on/off.)
      1. Center airbag sensor assembly
      2. Combination meter assembly (combination meter ECU)
      		 SRS warning light turns on Not possible (Light turns on) -
      Driver side seat belt warning light control (Sends "Fastened" and "Unfastened" signals according to the condition of the front seat inner belt assembly LH.)
      1. Combination meter assembly (combination meter ECU)
      2. Center airbag sensor assembly
      		 Driver side seat belt warning light does not operate Not possible (Recognition by driver not possible) -
      Front passenger side seat belt warning light control (Sends "Fastened" and "Unfastened" signals according to the condition of the front seat inner belt assembly RH.)
      1. Center airbag sensor assembly
      2. Combination meter assembly (combination meter ECU)
      		 Front passenger side seat belt warning light does not operate Not possible (Recognition by driver not possible) -
      Combination meter needle indicator (Controls the combination meter needle indicators in accordance with vehicle speed, engine speed and coolant temperature data.)
      1. Combination meter assembly (combination meter ECU)
      2. ECM, Brake actuator assembly (skid control ECU)
      		 VSC system does not operate Possible (Needle indicator does not move) Stored by combination meter ECU
      • U0100
      • U0129
      Warning display (Control that turns on/off or blinks the indicator lights based on warning information.)
      1. Combination meter assembly (combination meter ECU)
      2. ECM, Brake actuator assembly (skid control ECU), Power steering ECU assembly, 4WD control ECU assembly, Center airbag sensor assembly, ECU aggregation box assembly (certification ECU), Main body ECU (driver side junction block)
      		 ABS and brake warning lights turn on Not possible (Light turns on and off) -
      Warning buzzer (Control that sounds/stops the buzzers based on warning information.)
      1. Combination meter assembly (combination meter ECU)
      2. ECM, Brake actuator assembly (skid control ECU), Power steering ECU assembly, 4WD control ECU assembly, Center airbag sensor assembly, ECU aggregation box assembly (certification ECU), Main body ECU (driver side junction block)
      		 - Not possible (Buzzer sounds and stops) -
      Drive monitor (Controls drive monitor display based on vehicle speed pulse and fuel injection amount information.)
      1. Combination meter assembly (combination meter ECU)
      2. ECM, Brake actuator assembly (skid control ECU)
      		 Drive monitor numeric display is blank, vehicle speed pulse and tau integration stop Not possible (Recognition by driver possible based on behavior described) -
      Vehicle information transmission (Sends outside temperature, destination values, odometer values, vehicle speed signals and oil monitor reset information.)
      1. Combination meter assembly (combination meter ECU)
      2. Brake actuator assembly (skid control ECU)
      		 - Not possible (Recognition by driver not possible) -
      Warning light control (BRL, ABS) (Controls the warning light operation (on/off, blinking and DTC output).)
      1. Brake actuator assembly (skid control ECU)
      2. Combination meter assembly (combination meter ECU)
      		 Warning light turns on Not possible (Light turns on) -
      Warning light control (BRL, ABS, VSC-OFF, SLIP) (Controls the warning light operation (on/off, blinking and DTC output).)
      1. Brake actuator assembly (skid control ECU)
      2. Combination meter assembly (combination meter ECU)
      		 Warning light turns on Not possible (Light turns on) -
      ABS control (Controls the ABS in accordance with the yaw rate sensor signal.)
      1. Brake actuator assembly (skid control ECU)
      2. Yaw rate sensor assembly
      		 ABS system does not operate Possible (Light turns on) -
      TRC control (Controls the brake and engine torque during acceleration slip.)
      1. Brake actuator assembly (skid control ECU)
      2. ECM
      		 TRC system does not operate Possible (Light turns on) Stored by Brake actuator assembly (skid control ECU)
      • U0073
      • U0100
      VSC control (Controls VSC according to the yaw rate sensor and steering angle sensor signals.)
      1. Brake actuator assembly (skid control ECU)
      2. ECM, Yaw rate sensor assembly, Steering angle sensor
      		 VSC system does not operate Possible (Light turns on) Stored by Brake actuator assembly (skid control ECU)
      • U0073
      • U0100
      • U0123
      • U0124
      • U0126
      Air conditioning system (A/C control inside the vehicle.)
      1. Air conditioning ECU
      2. ECM, Combination meter assembly (combination meter ECU), Main body ECU (driver side junction block)
      		 A/C control stops Not possible (Recognition by driver possible due to A/C control stopping) -
      EPS control (Vehicle speed response type torque control.)
      1. Power steering ECU assembly
      2. ECM, Brake actuator assembly (skid control ECU)
      		 Decrease in EPS assist function (steering wheel becomes harder to turn) During VSC malfunction: Possible (Light turns on) Stored by Power steering ECU assembly
      • U0073
      • U0100
      • U0129
      • No EPS assist during initial check malfunction only
      • Engine speed value fixed and no effect on assist while driving
      		 During engine malfunction: Possible (Recognition by driver not possible)
      Entry function (Entry lock/unlock, entry luggage compartment open, entry warning, and entry illumination functions.)
      1. ECU aggregation box assembly (certification ECU), Main body ECU (driver side junction block)
      2. Combination meter assembly (combination meter ECU)
      • Entry lock/unlock does not operate
      • Entry warning does not operate and buzzer does not operate
      • Entry illumination does not operate
      • Operates entry unlock light
      • Entry warning function does not operate
      		 Not possible (Recognition by driver possible based on behavior described) Stored by Main body ECU (driver side junction block)
      • B1207
      • B2326
      Wireless function (Wireless lock/unlock and other functions.)
      1. Main body ECU (driver side junction block)
      2. ECU aggregation box assembly (certification ECU)
      		 Wireless lock/unlock does not operate Not possible (Recognition by driver possible based on behavior described)
      Engine system indicator display (Estimates degree of oil deterioration, controls the oil change indicator display on the combination meter and performs other functions.)
      1. ECM
      2. Combination meter assembly (combination meter ECU)
      		 Meter display clear not possible Not possible (Indicator does not turn on) -
      Electric load control (Performs idle up due to electric load or other factors.)
      1. ECM
      2. Air conditioning amplifier assembly, Power steering ECU assembly, Main body ECU (driver side junction block)
      		 Idle up due to electric load or other factors not possible Not possible (Idling speed change) -
      PTC heater (Performs idle up due to PTC heater and heater requests.)
      1. ECM
      2. Air conditioning amplifier assembly
      		 PTC heater does not operate Not possible (Heater performance decreases) -
      Charging control (Performs idle up due to charging requests.)
      1. ECM
      2. Air conditioning amplifier assembly, Combination meter assembly (combination meter ECU)
      		 Idle up due to charging request not possible Not possible (Recognition by driver possible based on behavior described) -
      Integrated control (VSC) (Estimates driver requested torque from the operation of the accelerator pedal, and performs torque characteristic control according to various conditions.)
      1. ECM
      2. Brake actuator assembly (skid control ECU), Steering angle sensor, Yaw rate sensor assembly, Power steering ECU assembly
      		 Integrated control not possible Not possible (Recognition by driver possible based on behavior described) -
      ECT system indicator display (The shift, switch, mode and other conditions are displayed on the combination meter.)
      1. ECM
      2. Combination meter assembly (combination meter ECU), Main body ECU (driver side junction block)
      		 - Not possible (Indicator does not turn on) -
      Neutral control (Reduces engine load and performs idle up.)
      1. ECM
      2. Brake actuator assembly (skid control ECU)
      		 Neutral control does not operate Possible (Recognition by driver possible based on behavior described) Stored by ECM
      • U0129
      Coast down shift (Changes the coast down shift point based on the A/C load.)
      1. ECM
      2. Air conditioning amplifier assembly
      		 Coast down shift does not operate Not possible (Coast down shock becomes stronger) -
      Cruise control (Automatically adjusts the throttle valve opening angle while driving.)
      1. ECM
      2. Combination meter assembly (combination meter ECU)
      		 Normal cruise control stops Not possible (Cruise main indicator blinks) -
      ATC-4WD (Controls the front/rear driving power distribution based on vehicle driving conditions.)
      1. 4WD control ECU assembly
      2. ECM, Brake actuator assembly (skid control ECU), Steering angle sensor
      		 4WD control stops (operates similarly to 2WD) Possible (Light turns on) Stored by 4WD control ECU assembly
      • U0073
      • U0100
      • U0126
      • U0129
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