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

INTRODUCTION TO ASC DIAGNOSIS

The active stability 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.

ABS WARNING LIGHT, ASC WARNING/OPERATION LIGHT AND BRAKE WARNING LIGHT CHECK

Check that ABS and brake warning light, ASC warning/operation light illuminate as follows.

Note. The brake warning light is used as a warning light for parking brake, brake fluid level, and EBD control.

Scheme 2

1. When the ignition switch is turned to the ON position, ABS and brake warning light, ASC warning/operation light illuminate.
2. The ABS and brake warning light, ASC warning/operation light illuminate for three seconds *1 and then turn OFF *2 .
3. Otherwise, check the diagnostic trouble code. NOTE: *1 : The ABS warning light may stay ON until the vehicle speed reaches 10 km/h. As far as ABS-ECU stores any diagnostic trouble code related to the wheel speed sensor malfunction or the motor malfunction as past trouble, ABS-ECU continues illuminating the ABS warning light until it verifies that the malfunction for that code is resolved (startup check). *2 : The brake warning light does not turn OFF when the parking brake is applied or the brake fluid level is lowered.

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. Each wheel speed detecting section is a kind of a pulse generator. It consists of the encoder (plate on which the north and south pole of magnet are arranged alternately) for detecting the wheel speed, which rotates at the same speed of the wheels, and the wheel speed sensor. This detecting section outputs the frequency pulse signals in proportion to the wheel speed.
2. The pulse signals generated by the wheel speed detecting section are sent to ASC-ECU. ASC-ECU uses the frequency of the pulse signals to determine the wheel speed.

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

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

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

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

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

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

1. Each wheel speed detecting section is a kind of a pulse generator. It consists of the encoder (plate on which the north and south pole of magnet are arranged alternately) for detecting the wheel speed, which rotates at the same speed of the wheels, and the wheel speed sensor. This detecting section outputs the frequency pulse signals in proportion to the wheel speed.
2. The pulse signals generated by the wheel speed detecting section 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.

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. 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, and 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 hydraulic 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.

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.

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.

The ASC-ECU is energized by the valve power supply circuit (terminal No. 32). 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. 4) energizes the ASC-ECU.

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

ASC-ECU receives signals necessary for the operations of ABS or ASC from the engine control module, TCM, AWD-ECU, ETACS-ECU, and the steering wheel sensor via the CAN bus lines.

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

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

1. 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.

Perform the master cylinder pressure sensor calibration to store the calibrated value in the ASC-ECU. At the same time, the calibrated value of cut valve and inlet valve are stored.

The ASC-ECU stores diagnostic trouble codes and failure information in the EEPROM*.

ASC-ECU (EEPROM*) contains the power supply circuit (terminal No. 2).

Note. *:EEPROM (Electrical Erasable and Programmable ROM)

ASC-ECU communicates with the engine control module, TCM, 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 control module 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.

SYSTEM OPERATION

When ASC OFF display flashes at a rate of 2 Hz, TCL control by brake force is prohibited.

TECHNICAL DESCRIPTION (COMMENT)

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 reaches the specified value or more, ASC-ECU flashes the ASC OFF display at a rate of 2 Hz to warn the driver that the brake controllability by TCL is decreased by the reduced braking force. Consequently, ASC-ECU prohibits the TCL control (brake control only) until it determines that the estimated temperature of the brake pad is normal. NOTE: Besides severe driving, brake pad condition and brake drag are also suspected as a cause of overheat. After the ASC OFF display illumination turns off, check the brake pad condition and brake drag.

1. When the parking brake switch is turned "ON", the combination meter terminal No. 4 is grounded, and the brake warning light illuminates.
2. When reduction of the brake fluid amount is detected, the brake fluid level switch is turned from "ON" to OFF. ETACS-ECU monitors the brake fluid level switch, and instructs the combination meter via the CAN bus line to illuminate the brake warning light.

This may be caused by ground fault in the parking brake switch circuit.

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.

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

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 ASC warning display 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 ASC OFF display to the combination meter through ETACS-ECU via CAN communication.
2. By the operation of ASC OFF switch, the ASC OFF display illuminates when the ASC function is stopped.
3. When the ASC OFF switch is pressed for 3 seconds or more, the ASC system turns OFF.
4. When the ASC OFF switch is pressed for 15 seconds or more, the ASC is kept in ON state.

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

INSPECTION PROCEDURE 9: ASC OPERATION DISPLAY STAYS ON AFTER THE ENGINE IS STARTED

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

The ETACS-ECU terminal No. 15 is grounded by pressing the ASC OFF switch and illuminate the ASC OFF indicator. The ON/OFF state of the ASC OFF switch is transferred from ETACS-ECU to ASC-ECU via the CAN bus line.

INSPECTION PROCEDURE 11: ABNORMALITY IN BRAKE OPERATION

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.

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. ASC-ECU contains the power supply circuit (terminal No. 2) for ASC-ECU. The power is supplied from the fusible link No. 34 through the multi-purpose fuse No. 17.
3. ASC-ECU contains the power supply circuit (terminal No. 8) for ASC-ECU. When the ignition switch (IG1) is turned ON, the voltage is applied to the relay incorporated in ETACS-ECU to turn ON the relay, and the power is supplied from the fusible link No. 34 through multi-purpose fuse No. 12.
4. 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.
5. When malfunction occurs in ASC-ECU power supply, the communication with scan tool becomes unavailable.

1. Steering wheel sensor contains the power supply circuit (terminal No. 2) for Steering wheel sensor. The power is supplied from the ETACS-ECU (terminal No. 5). The power is supplied from the fusible link No. 34 through the multi-purpose fuse No. 12.
2. When malfunction occurs in Steering wheel sensor power supply, the communication with scan tool becomes unavailable.

1. The slope gradient may be low.
2. The vehicle is not completely stationary.
3. A failure may have occurred in the calibration of the G and yaw rate sensor or brake fluid pressure sensor.
4. The parking brake switch may be seized, which causes the HSA to fail to start the operation.
5. A problem (noise interference) may have occurred in the CAN bus line, resulting in an improper communication with ASC-ECU or each ECU. NOTE: The HSA does not work even when the wheel speed sensor output pulse (vehicle moved) while the vehicle is parked. The HSA is affected by the loading conditions and vehicle posture at the occurrence of phenomenon. When checking the HSA operation in actual driving, carry out the check on the vehicle with one occupant (driver) only.