Vehicle Stability Control System: Fail-Safe

• 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 ABS, TRAC and VSC systems were not installed.

  The 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, immediately stop the operation.

  If system components have any malfunction during control, gradually stop 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 ABS, BA, TRAC, A-TRAC, VSC, downhill assist control and hill-start assist control system control is prohibited.

1. ABS, EBD and BA system:

   HINT:

   A malfunction in either the ABS or BA system will result in an identical operation, with ABS, BA, TRAC, A-TRAC, VSC, downhill assist control and hill-start assist control system control prohibited.

   MALFUNCTION AREA CONTROL METHOD TABLE
   
   

   Malfunction Area	Control Method
   ABS system	ABS, BA, TRAC, A-TRAC, VSC, downhill assist control and hill-start assist control prohibited
   BA system	ABS, BA, TRAC, A-TRAC, VSC, downhill assist control and hill-start assist control prohibited
   EBD system	ABS, EBD, BA, TRAC, A-TRAC, VSC, downhill assist control and hill-start assist control prohibited

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

   HINT:

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

If the TRAC, A-TRAC, downhill assist control, 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 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 downhill assist control system, the downhill assist control indicator light also comes on), the systems automatically return to normal operating conditions.
• As this is not a malfunction, no DTC will be recorded.