VEHICLE STABILITY CONTROL SYSTEM FAIL-SAFE CHART

  1. FAIL-SAFE OPERATION

    • If there is a problem with sensor signals or actuator systems, the skid control ECU (brake actuator assembly) prohibits power supply to the brake actuator assembly and informs the ECM of VSC system failure.

      The brake actuator assembly turns off each solenoid and the ECM shuts off VSC control (traction control signal) from the skid control ECU (brake actuator assembly) accordingly, which turns out to be as if the ABS, TRC/TRAC and VSC systems were not installed.

      The ABS control will be prohibited, but EBD control will continue as much as possible. If EBD control is impossible, the brake warning light will come on to warn the driver.

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    • If system components have any malfunctions before starting control, immediately stop the operation. If system components have any malfunctions during control, gradually stop the control so as not to trigger a sudden change in vehicle conditions.

      If it is impossible to control the systems, the warning light comes on to inform the driver of termination of the systems.

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    Tip:

    If the brake booster encounters a malfunction, brake performance is gradually lost and ABS, BA, TRC/TRAC and VSC systems are prohibited.

    Table 1. ABS, EBD and BA Systems

    Malfunction Area

    Control Method

    ABS system

    ABS, BA, TRC/TRAC and VSC control prohibited

    BA system

    ABS, BA, TRC/TRAC and VSC control prohibited

    EBD system

    ABS, EBD, BA, TRC/TRAC and VSC control prohibited

    Tip:

    A malfunction in either the ABS or BA system will result in an identical operation, with ABS, BA, TRC/TRAC and VSC system control prohibited.

    Table 2. TRC/TRAC and VSC Systems

    Malfunction Area

    Control Method

    Engine control system

    (TRC/TRAC system)*1

    (TRC/TRAC and VSC systems)*2

    Before control: Disables control

    During control: Uses only the brakes to perform control

    Brake control system

    (VSC system)

    Before control: Disables control

    During control: Uses only the engine to perform control

    Brake control system

    (TRC/TRAC system)

    Before control: Disables control

    During control: Disables control (by gradually ending control)

    • *1: for 2AR-FE, 3ZR-FAE, 3ZR-FE

    • *2: for 1AD-FTV, 2AD-FHV, 2AD-FTV

    Tip:

    As for the TRC/TRAC and VSC systems, different systems prohibit different controls depending on the malfunctioning part.