Toyota Avalon Service & Repair Manual: Fail-safe Chart

FAIL-SAFE CHART

FAIL-SAFE OPERATION

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

    The brake actuator assembly turns off the solenoids and the ECM stops its VSC control according to signals from the skid control ECU. The vehicle will operate in a manner similar to a vehicle that is not equipped with ABS, TRAC, secondary collision brake, VSC and brake hold systems.

    ABS control will be prohibited, but EBD control will continue to the extent that EBD control is possible. If EBD control is impossible, the brake system warning light (red indicator) will come on to warn the driver.

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  • If a VSC system component malfunctions before VSC control begins, VSC control will be prohibited. If a system component malfunctions during VSC control, the system will gradually stop performing control so as not to trigger a sudden change in vehicle operation.

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

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  • If the skid control ECU (brake actuator assembly) detects that a system related to the airbag system or the engine control system is malfunctioning, it will prohibit operation of the secondary collision brake in order to prevent further malfunctions and to protect the systems.
  • When a malfunction occurs in the VSC system or electric parking brake system, brake hold control prohibits brake hold operation to prevent incorrect operation and protect the system.
ABS, EBD and BA System

Item

Operation

Malfunction in the ABS.

ABS, BA, TRAC and VSC control prohibited.

Brake hold control prohibited.

Malfunction in the BA system.

ABS, BA, TRAC and VSC control prohibited.

Brake hold control prohibited.

Malfunction in the EBD system.

ABS, EBD, BA, TRAC and VSC control prohibited.

Brake hold control prohibited.

TRAC and VSC System

Item

Operation

Malfunction in the engine control system (TRAC and VSC systems).

Before control: Disables control.

During control: Uses only the brakes to perform control.

Malfunction in the brake control system (VSC system).

Before control: Disables control.

During control: Uses only the engine to perform control.

Malfunction in the brake control system (TRAC system).

Before control: Disables control.

During control: Disables control (by gradually ending control).

Secondary Collision Brake System

Item

Operation

Malfunction in the airbag system (secondary collision brake system).

Before control: Disables control.

During control: Uses only the brakes to perform control.

Malfunction in the engine control system (secondary collision brake system).

Before control: Disables control.

During control: Uses only the brakes to perform control.

    Excessive Brake Pedal Travel (No Fluid Leaks and No Air in System)

    Freeze Frame Data

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