Lexus ES: Fail-safe Chart
FAIL-SAFE CHART
FAIL-SAFE CHART
(a) When the skid control ECU (brake actuator assembly) detects a solenoid valve malfunction or abnormal signal from a sensor, the brake actuator assembly cuts power and sends a signal indicating a malfunction of the electronically controlled brake system to the ECM.
HINT:
Based on signals sent from the skid control ECU (brake actuator assembly), the brake actuator assembly prevents the solenoids from operating, and the ECM no longer accepts fuel-cut request signals from electronically controlled brake system.
(b) If a malfunction of ABS, brake assist, TRAC or VSC is detected, operation of the function is prohibited and the related warning lights illuminate.
The EBD function can still operate even if operation of the ABS function is prohibited. However, if the EBD function is also affected, operation of the EBD system will be prohibited and the brake warning light / red (malfunction) illuminates.
HINT:
When a component of the electronically controlled brake system is in fail-safe mode, operation is prohibited. However, if the system enters fail-safe mode while braking is being controlled, control is gradually suspended to prevent sudden changes in vehicle behavior.
(c) If a malfunction in the electronically controlled brake system or electric parking brake system is detected, control by the brake hold function is prohibited to prevent undesired operation and to protect the system.
HINT:
When control by the brake hold system is prohibited, the brake hold switch (No. 3 combination switch assembly) is ON and the following conditions are met, the brake hold indicator will blink.
-
Vehicle conditions:
- The driver door is closed.
- The driver seat belt is fastened.
(d) If the skid control ECU (brake actuator assembly) detects a malfunction in the SRS system, secondary collision brake control is prohibited to prevent undesired operation and to protect the system.
HINT:
When control is prohibited, a message is displayed on the multi-information display in the combination meter assembly.
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. |
| 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). |
| 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. |
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