Fail-Safe Chart

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

  The hydraulic brake booster turns off each solenoid and the ECM shuts off VSC control (traction control signal) from the skid control ECU accordingly, which results in the vehicle being controlled as if the multi-terrain ABS, A-TRAC and VSC systems were not installed.

  Multi-terrain ABS control is prohibited, but EBD control continues to the extent that it is possible. If EBD control is impossible, the BRAKE warning light comes on to warn the driver. Refer to DIAGNOSIS SYSTEM .

• If a system component has any malfunction before control begins, operation is prohibited.

  If a system component has any malfunction during control, the system will gradually stop operating 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. Refer to DIAGNOSIS SYSTEM .

• VSC control continues as much as possible while the TRAC OFF indicator light is on even when the engine has failed.

HINT: 

If the hydraulic brake booster encounters a malfunction, brake performance is gradually lost and multi-terrain ABS, BA, A-TRAC, VSC, CRAWL and hill-start assist control system control is prohibited.

1. Multi-terrain ABS, EBD and BA system:

   Area of Malfunction	Control Method
   Multi-terrain ABS system	Multi-terrain ABS, BA, A-TRAC, VSC, CRAWL and hill-start assist control prohibited.
   BA system	Multi-terrain ABS, BA, A-TRAC, VSC, CRAWL and hill-start assist control prohibited.
   EBD system	Multi-terrain ABS, EBD, BA, A-TRAC, VSC, CRAWL and hill-start assist control prohibited.

2. A-TRAC, VSC, CRAWL and hill-start assist control system:

   HINT: 

   As for the A-TRAC, VSC, CRAWL and hill-start assist control systems, different systems prohibit different controls according to the malfunctioning part.

   Area of Malfunction	Control Method
   Engine control system	Before control starts: Control is disabled. During control: Control is disabled (VSC is enabled).
   Brake control system (VSC system)	Before control starts: Control is disabled. During control: Control is disabled.
   Brake control system (A-TRAC, CRAWL and hill-start assist control systems)	Before control starts: Control is disabled. During control: Control is gradually disabled.

If the A-TRAC, CRAWL or hill-start assist control system has been used constantly for a long time, the temperature of the hydraulic brake booster may excessively increase. If the temperature excessively increases, the skid control buzzer will sound intermittently. If the temperature increases even more, the skid control buzzer sounds for 3 seconds and the indicator light either comes on or blinks.

HINT: 

• When the CRAWL indicator light turns off after blinking, CRAWL temporarily becomes nonfunctional, but after the temperature has decreased, pressing the CRAWL switch again will activate CRAWL (even when the temperature decreases, CRAWL will not reactivate automatically).
• If the systems automatically return to normal operating conditions, the slip indicator light goes off (in the case of the CRAWL system, the CRAWL indicator light also comes on).
• As this is not a malfunction, no DTC will be stored.