Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Fail-safe Chart

FAIL-SAFE CHART

FAIL-SAFE FUNCTION OF CONTROL SYSTEM

(a) When a malfunction is detected in the brake control system, the skid control ECU (brake booster with master cylinder assembly) turns the ABS warning, brake warning / red (malfunction), brake warning / yellow (minor malfunction) and slip indicator lights on, flashes the brake hold operated indicator light*, as well as prohibits ABS, BA, TRAC, VSC, secondary collision brake and brake hold operation.

• *: The brake hold switch (electric parking brake switch assembly) is turned on under the following vehicle conditions.
  • Vehicle Conditions:
    1. The driver side door is closed.
    2. The driver side seat belt is fastened.

(b) If the skid control ECU (brake booster with master cylinder assembly) detects that a system related to the hybrid control system is malfunctioning, it will prohibit operation of the TRAC and VSC systems in order to prevent further malfunctions and to protect the systems.

(c) Brake hold control prohibits brake hold operation in order to protect the system and prevent improper operation when the electronically controlled brake system, electric parking brake system or hybrid control system is malfunctioning.

(d) If the skid control ECU (brake booster with master cylinder assembly) detects that a system related to the airbag system is malfunctioning, it will prohibit operation of the secondary collision brake in order to prevent further malfunctions and to protect the systems.

• *: Only during brake hold control

FAIL-SAFE FUNCTION OF HYDRAULIC SYSTEM

(a) If a malfunction is detected in the skid control ECU (brake booster with master cylinder assembly), brake actuator (brake booster with master cylinder assembly) or an individual sensor, control will be stopped and brake effort will be generated by the hydraulic brake booster (brake booster with master cylinder assembly).

(b) If brake control is stopped due to a malfunction in the hydraulic pressure source, the pressure generated in the master cylinder by the driver is applied to the wheel cylinders to ensure braking force.