Active Stability Control System (Asc): Overview Mitsubishi Outlander II

GENERAL INFORMATION

ASC (Active Skid Control System) has been installed.

1. The ASC system integrates the traction control function and skid control function.
2. When Traction control function detects the slip of the driving wheel (ex. during startup on slippery surfaces), it automatically applies the brakes to control the wheel slip ratios. At the same time, Traction control function reduces the engine output and prevents the wheel spin.
3. Skid control function responds to driving conditions and reduces the engine output and applies brake force to four wheels independently to control the vehicle behavior.
4. Fail-safe function assures the safety.
5. Serviceability improvement
6. For reduced wiring harnesses and secure data communication, the CAN* communication has been adopted as a tool of communication with another ECU.

Note. *For more information about CAN (Controller Area Network), refer to GENERAL INFORMATION . ABS and ASC are controlled by ASC-ECU.

Scheme 46

STOPLIGHT SWITCH SPECIFICATION

INTRODUCTION TO ASC DIAGNOSIS

The active skid control system (ASC) operates differently from conventional brake systems. These differences include sounds, sensations, and vehicle performance that owners and service technicians who are not familiar with ASC may not be used to.

Some operational characteristics may seem to be malfunctions, but they are simply signs of normal ASC operation. When diagnosing the ASC system, keep these operational characteristics in mind. Inform the owner of the kind of performance characteristics to expect from an ASC-equipped vehicle.

CIRCUIT OPERATION

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. The wheel speed sensor is a kind of a pulse generator. It consists of encoders (a plate on which north and south pole sides of the magnets are arranged alternately) for detecting the wheel speed which rotates at the same speed of the wheels and wheel speed sensors. This sensor outputs frequency pulse signals in proportion to the wheel speed.
2. The pulse signals, which the wheel speed sensor creates, are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

1. ASC-ECU contains the power supply circuit (terminal No. 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in ASC-ECU.
2. The valve relay, which is incorporated in ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on, or the recurrent system check is in progress.
3. ASC-ECU activates the solenoid valve by turning on its driving transistor.

1. ASC-ECU contains the power supply circuit (terminal No. 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in ASC-ECU.
2. The valve relay, which is incorporated in ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on, or the recurrent system check is in progress.

1. ASC-ECU contains the power supply circuit (terminal No. 1) for the pump motor. The pump motor is energized by the motor switch, which is incorporated in ASC-ECU.
2. The pump motor switch, which is incorporated in ASC-ECU, is always off unless the motor and solenoid valve check is activated when the vehicle is started.
3. ASC-ECU activates the pump motor by turning on the ECU built-in pump motor switch.

1. ASC-ECU contains the power supply circuit (terminal No. 1) for the pump motor. The pump motor is energized by the motor switch, which is incorporated in ASC-ECU.
2. The pump motor switch, which is incorporated in ASC-ECU, is always off unless the motor and solenoid valve check is activated when the vehicle is started.
3. ASC-ECU activates the pump motor by turning on the ECU built-in pump motor switch.

The brake fluid pressure sensor is incorporated in the hydraulic unit. When the brake pedal is depressed, the pressure sensor detects the brake pressure applied from the master cylinder, converts this pressure into the voltage signal, and outputs it.

The brake fluid pressure sensor is incorporated in the hydraulic unit. When the brake pedal is depressed, the pressure sensor detects the brake pressure applied from the master cylinder, converts this pressure into the voltage signal, and outputs it.

ETACS-ECU sends the ON signal generated when the brake pedal is depressed and OFF signal generated when it is released to ASC-ECU via the CAN bus lines.

ASC-ECU receives the low level signal of the brake fluid level switch in ETACS-ECU via the CAN bus lines. When the brake fluid level is lower than the specified.

DTC C123B: Prolonged operation of ASC

ASC-ECU controls ASC by calculating the data sent from the wheel speed sensor, the steering wheel sensor, and the G and yaw rate sensor.

1. The ASC-ECU always monitors itself while the system is in operation. If the ASC-ECU detects any faults it will set this DTC
2. ASC-ECU controls ASC by calculating the data sent from the wheel speed sensor, the steering wheel sensor, and the G and yaw rate sensor.

1. The ASC-ECU is energized by the valve power supply circuit (terminal No. 26).
2. When the power is supplied from the ignition switch (IG1) to the IG1 relay in ETACS-ECU, IG1 relay is turned on. At this time, the valve power supply circuit (terminal No. 26) energizes the ASC-ECU.

1. The ASC-ECU is energized by the valve power supply circuit (terminal No. 26).
2. When the power is supplied from the ignition switch (IG1) to the IG1 relay in ETACS-ECU, IG1 relay is turned on. At this time, the valve power supply circuit (terminal No. 26) energizes the ASC-ECU.

ASC-ECU sends the signal to the engine ECU as necessary to decrease the engine output for the ASC system operation.

ASC-ECU receives signals necessary for the operations of ABS, ASC, and TCL from the engine ECU, A/T-ECU, AWD-ECU, ETACS-ECU, and the steering wheel sensor via the CAN bus lines.

ASC-ECU receives vehicle information from the engine ECU and stores it.

ASC-ECU receives the vehicle information stored in the ETACS-ECU via CAN bus lines.

1. ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
2. The G and yaw rate sensor outputs the signal to ASC-ECU via the CAN bus lines.

1. ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
2. The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

1. ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
2. The G and yaw rate sensor outputs the signal to ASC-ECU via the CAN bus lines.

1. ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
2. The G and yaw rate sensor outputs the signal to ASC-ECU via the CAN bus lines.

When the brake pedal is depressed, the brake fluid pressure sensor integrated in the hydraulic unit detects the brake fluid pressure applied from the master cylinder, converts the pressure value into voltage signal, and outputs it.

1. ASC-ECU supplies power to the G and yaw rate sensor at the terminal No. 1.
2. The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

ASC-ECU stores the calibrated value of the G and yaw rate sensor, steering wheel sensor, and brake fluid pressure sensor.

Steering wheel sensor outputs the signal to ASC-ECU via the CAN bus lines.

Steering wheel sensor stores the neutral position learned by the scan tool. When the neutral position has not been stored in the steering wheel sensor yet, the steering wheel sensor outputs the signal indicating that it does not have neutral position.

1. Steering wheel sensor sends its status signal to ASC-ECU.

ASC-ECU communicates with the engine ECU, A/T-ECU, AWD-ECU, the steering wheel sensor, and ETACS-ECU via the CAN bus lines.

The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

Engine-related signals are sent or received to and from between ASC-ECU and engine ECU via CAN bus lines.

The steering wheel sensor outputs the steering wheel status to ASC-ECU via the CAN bus lines.

The G and yaw rate sensor outputs the signal to ASC-ECU via the special CAN bus lines.

ASC-ECU receives the vehicle information stored in the ETACS-ECU via CAN bus lines.

ASC-ECU receives the vehicle information stored in the ETACS-ECU via CAN bus lines.

TECHNICAL DESCRIPTION (COMMENT)

When scan tool cannot communicate with the ABS/TCL/ASC system, the CAN bus line, ASC-ECU power supply circuit system, or ASC-ECU may be faulty.

SYSTEM OPERATION

When ASC OFF indicator light flashes at a rate of 2 Hz, traction control by brake force is prohibited.

This operation is performed for the following reasons and is not a malfunction.

1. ASC-ECU calculates the estimated temperature of the brake pad. In general, as the brake pad temperature increases, the coefficient of friction for the brake pad becomes smaller, resulting in the reduced braking force. When the estimated temperature of the brake pad exceeds the specification, ASC-ECU flashes the ASC OFF indicator light at a rate of 2 Hz to warn the driver that the controllability of TCL is decreased by the reduced braking force. Consequently, ASC-ECU prohibits the traction control by brake force until it determines that the estimated temperature of the brake pad is at normal value.

When the parking brake switch is turned ON, the combination meter terminal No. 4 is grounded, and the brake warning light illuminates.

The following cases may have occurred.

1. Ground fault in the parking brake switch circuit.
2. The EBD is defective.
3. The brake fluid level in the brake fluid reservoir is the specified value or lower.

1. ASC-ECU sends the illumination request signal of the ABS warning light to the combination meter through ETACS-ECU via CAN communication.
2. ASC-ECU illuminates the ABS warning light via ETACS-ECU for approximately 3 seconds for valve check with the ignition switch turned to the ON position.

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

ASC-ECU sends the illumination request signal of the break warning light to the combination meter through ETACS-ECU via the CAN communication.

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

1. ASC-ECU sends the illumination request signal of the ABS warning light to the combination meter through ETACS-ECU via CAN communication.
2. ASC-ECU illuminates the ABS warning light via ETACS-ECU for approximately 3 seconds for valve check with the ignition switch turned to the ON position.
3. The ASC-ECU turns off the ABS warning light if an ABS error is not detected after illuminating the ABS warning light for approximately 3 seconds.

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

ASC-ECU sends the illumination request signal of the ASC indicator light to the combination meter through ETACS-ECU via the CAN communication.

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

ASC-ECU sends the illumination request signal of the ASC OFF indicator light to the combination meter through ETACS-ECU via CAN communication.

This may be caused by faults in the CAN bus line, ETACS-ECU, combination meter or ASC-ECU.

The ETACS-ECU terminal No. 15 is earthed by pressing the ASC switch. The active or not active state of the ASC switch is transferred from ETACS-ECU to ASC-ECU via the CAN bus line.

This may be caused by the open circuit in the ASC switch circuit.

1. Although the cause of the trouble cannot be clearly resolved since it depends on the running status and road surface condition, the malfunction of the hydraulic circuit may occur if any diagnostic trouble code is not detected.

In case of this trouble symptom, traction control function or skid control function operation may be disabled. Diagnostic trouble code may be set by the traction control function or skid control function.

1. The ASC-ECU power supply signal energized by the ignition switch (IG1) is transmitted to ASC-ECU (terminal No. 4) via the multi-purpose fuse No.12.
2. The ASC-ECU power supply and the valve power supply are transmitted to ASC-ECU (terminal No. 32) via the fusible link No. 27.
3. When malfunction occurs in ASC-ECU power supply, the communication with scan tool becomes unavailable.