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 turns out to be as if the Multi-terrain ABS, A-TRAC and VSC systems were not installed.

  The Multi-terrain ABS control will be prohibited, but EBD control continues as much as possible. If EBD control is impossible, the BRAKE warning light comes on to warn the driver (See DIAGNOSIS SYSTEM  ).

• If system components have any malfunction before starting control, the fail-safe function immediately stops the operation.

  If system components have any malfunction during control, the fail-safe function gradually stops 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 (See DIAGNOSIS SYSTEM  ).

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:
   MALFUNCTION AREA
   
   

   Malfunction Area	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.

   MALFUNCTION AREA
   
   

   Malfunction Area	Control Method
   Engine control system (A-TRAC and VSC systems)	Before control: Disables control During control: Uses only brakes to perform control
   Brake control system (VSC system)	Before control: Disables control During control: Uses only engine to perform control
   Brake control system (A-TRAC, CRAWL and hill-start assist control systems)	Before control: Disables control During control: Disables control (by gradually ending control)

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:

• If the SLIP indicator light goes off (as for the CRAWL control system, the CRAWL control indicator light also comes on), the systems automatically return to normal operating conditions.
• When the CRAWL indicator light turns off after blinking, CRAWL control temporarily becomes nonfunctional, but after the temperature of the hydraulic brake booster drops, CRAWL control becomes operational.
• As this is not a malfunction, no DTC will be stored.