ACTIVE STABILITY CONTROL SYSTEM (ASC)
ACTIVE STABILITY CONTROL SYSTEM (ASC)
35C-16
FAIL-SAFE AND DIAGNOSTIC FUNCTIONS
ASC-ECU constantly monitors the input and output
signals. If an error is detected in the system,
ASC-ECU sends a fail signal and the corresponding
indicator lamp is illuminated or blinks. Various con-
trols are processed depending on the cause of mal-
function as shown below.
ASC-ECU has the following functions for easier sys-
tem checks.
• Diagnosis code set
• Service data output
• Actuator test
• Freeze frame data output
All the above items can be diagnosed using
M.U.T.-III.
CALIBRATION
After the steering wheel sensor and hydraulic unit
(integrated with ASC-ECU and G & yaw rate sensor)
have been replaced with new ones, calibration must
be performed using M.U.T.-III*.
NOTE:
.
•
M.U.T.-III uses the ABS data list.
•
*: For calibration, refer to Workshop Manual.
DESCRIPTION OF CONSTRUCTION AND OPERATION
M2355002000563
STABILITY CONTROL OPERATION
ASC-ECU receives various kinds of information from
the engine-ECU, 4WD-ECU, ETACS-ECU,
CVT-ECU, steering wheel sensor, G & yaw rate sen-
sor, and wheel speed sensor. When ECU determines
the vehicle runs in the oversteer or understeer direc-
tion based on the signal sent from these sensors,
ASC-ECU drives each valve and pump motor and
controls the braking force to be applied to the
wheels.
When the system increases the fluid pressure auto-
matically, it closes the cut valve to shut off the pres-
sure line to the suction valve, and drives the pump
motor. For example, when the vehicle runs in the
oversteer direction while turning to the right,
ASC-ECU supplies the brake fluid from the pump to
the front left wheel to apply the braking force on it.
ASC-ECU, the engine ECU, and 4WD-ECU commu-
nicate with each other via CAN. When the accelera-
tor pedal is depressed too far, the signal requesting
the engine output reduction is sent to the engine
ECU. Depending on the situation, 4WD control
amount limitation signal is sent to the ASC-ECU to
secure the ASC controllability.
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