Traction Control/active Skid Control System: Overview Mitsubishi Eclipse IV рестайлинг

GENERAL DESCRIPTION

Traction Control/Active Skid Control System (TCL/ASC) is available for 3.8L engine "S" grade models as optional equipment.

1. The TCL/ASC is a combination system of active skid control system (ASC) and traction control system (TCL). The ASC avoids a dangerous vehicle attitude by limiting the engine output and braking a set of wheels (front left and right rear, or right front and left rear) according to driving conditions. The TCL prevents wheel spinning at vehicle start.
2. Fail-safe function ensures safety is maintained
3. Diagnostic function provides improved serviceability
4. To shorten the lines and enhance data transmission reliability, communication with other ECU is performed over a CAN (Controller Area Network).

Scheme 185

PART FUNCTIONS

Scheme 186

TCL/ASC OPERATION SOUNDS AND SENSATIONS

During normal operation, the TCL/ASC makes several sounds that may seem unusual at first

1. A whining sound is caused by the TCL/ASC hydraulic unit motor.
2. When pressure is applied to the brake pedal, the pulsation of the pedal causes a scraping sound.
3. When the brakes are applied firmly, the TCL/ASC operates, rapidly applying and releasing the brakes many times per second. This repeated application and release of braking forces can cause the suspension to make a thumping sound and the tires to squeak.

ASC OFF SWITCH OPERATION AND THEIR RESPECTIVE CONTROL

ASC OFF SWITCH OPERATION AND THEIR RESPECTIVE CONTROL

Note. The ASC returns to the active state automatically when the ignition switch is turned to the ON position.

TCL/ASC INDICATOR, ASC OFF INDICATOR AND THEIR OPERATION PATTERN

TCL/ASC INDICATOR, ASC OFF INDICATOR AND THEIR OPERATION PATTERN

OVERVIEW OF CONTROL

The TCL/ASC-ECU detects vehicle movement based on information from various sensors and calculates a model of ideal vehicle movement. After comparing actual and ideal movements, it acts to bring the actual vehicle movement closer to the ideal model by controlling specific wheel brake force and governing engine output. It restrains under-steering and over-steering through a corrective yaw moment, as explained on the following pages.

Scheme 187

The ASC manages the vehicle attitude by creating a yaw moment from altering the balance between the cornering force and each wheel's braking mechanism.

For example, on a slippery surface, if the vehicle tends to be under-steered contrary to the driver's intention, a yaw moment (a rotational moment) is created to restrain the under-steering by increasing the rear-inside braking force. On the other hand, when the vehicle tends to be over-steered, a yaw moment (a restorative moment) is created to restrain the over-steering by increasing the front-outside braking force. Furthermore, when it is determined that the vehicle is over-speeding, safe and stable cornering is enabled by deceleration from restricting engine output.

Scheme 188

EXAMPLE OF OPERATION OF TCL

The TCL prevents drive force loss during slipping of the drive wheels by automatically applying the brakes and sending engine torque reduction signal to the ECM < M/T > or PCM < A/T > when the drive wheels slip or when driving on partly low-friction surfaces.

INTRODUCTION TO TCL/ASC DIAGNOSIS

The TCL/ASC is a system that has added the cut valve and suction valve to the conventional ABS system. These valves are used to control each of the road wheels independently. These differences include sounds, sensations, and vehicle performance that owners and service technicians who are not familiar with TCL/ASC may not be used to. Some operational characteristics may seem to be malfunctions, but they are simply signs of normal TCL/ASC operation. When diagnosing the TCL/ASC system, keep these operational characteristics in mind. Inform the owner of the kind of performance characteristics to expect from an TCL/ASC-equipped vehicle.

CIRCUIT OPERATION

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. A toothed ABS rotor generates a voltage pulse as it moves across the pickup field of each ABS sensor.
2. The amount of voltage generated at each wheel is determined by the clearance between the ABS rotor teeth and the ABS sensor, and by the speed of rotation.
3. Sends alternating current signals at frequencies which are proportional to the rotation speeds of each wheel to the TCL/ASC electronic control unit (TCL/ASC-ECU).
4. The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

1. The TCL/ASC-ECU contains the power supply circuit (terminal 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in the TCL/ASC-ECU.
2. The valve relay, which is incorporated in the TCL/ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on.
3. The TCL/ASC-ECU activates the solenoid valve by turning on its driving transistor.

1. The TCL/ASC-ECU contains the power supply circuit (terminal 1) for the pump motor. The pump motor is energized by the motor relay, which is incorporated in the TCL/ASC-ECU.
2. The motor relay, which is incorporated in the TCL/ASC-ECU, is always off unless the motor solenoid valve check is activated when the vehicle is started.
3. The TCL/ASC-ECU activates the pump motor by turning on the ECU built-in motor relay when the ABS is working.

1. The TCL/ASC-ECU contains the power supply circuit (terminal 32) for the solenoid valve. The solenoid valve is energized by the valve relay, which is incorporated in the TCL/ASC-ECU.
2. The valve relay, which is incorporated in the TCL/ASC-ECU, is always energizing the solenoid valve unless the initial check is in progress when the ignition switch is turned on.

1. The "ON" signal when the brake pedal is pressed or the "OFF" signal when the brake pedal is released is input to the TCL/ASC-ECU (terminal 41.)

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

1. The G and yaw rate sensor is energized by the ignition switch (IG1) through multi-purpose fuse 2 and the TCL/ASC-ECU terminal 4.

1. The TCL/ASC-ECU and the steering wheel sensor are connected each other via a CAN bus line, and the sensor sends the steering wheel angle and angular velocity information to the ECU.

The TCL/ASC-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 2 and the TCL/ASC-ECU terminal 4.

The TCL/ASC-ECU and the steering wheel sensor are connected each other via a CAN bus line, and the sensor sends the steering wheel angle information to the ECU.

1. The steering wheel sensor is energized via the ignition switch, and communicates the TCL/ASC-ECU via a CAN bus-line.
2. The steering wheel sensor has a self-diagnosis function and a memory function. If the diagnosis function finds a trouble, it sends these DTC codes to the TCL/ASC-ECU. Then the ECU will illuminate the TCL/ASC indicator light. At this time, the TCL/ASC-ECU sets DTC No. C1506 (Steering angle sensor error).

TECHNICAL DESCRIPTION (COMMENT)

If the scan tool (M.U.T.-III Sub Assembly) can not communicate with the ABS system, the CAN bus lines may be defective. If the ABS system does not work, the TCL/ASC-ECU or its power supply circuit may be defective.

If the scan tool (M.U.T.-III Sub Assembly) can not communicate with the steering wheel sensor, the CAN bus lines may be defective. If the ASC system does not work, the steering wheel sensor or its power supply circuit may be defective.

1. The TCL/ASC-ECU is energized by the ignition switch (IG1) through multi-purpose fuse 2 and the TCL/ASC-ECU terminal 4.
2. If the power supply to the TCL/ASC-ECU has failed, scan tool MB991958 will not be able to communicate with it.

1. The steering wheel sensor is energized by the ignition switch (IG1) through multi-purpose fuse 2 and the steering wheel sensor terminal 2.
2. If the power supply to the steering wheel sensor has failed, scan tool (M.U.T.-III Sub Assembly) will not be able to communicate with it.

1. TCL/ASC-ECU send the illumination signal of "ASC OFF" indicator and TCL/ASC work indicator to the combination meter via the CAN communication.
2. TCL/ASC-ECU operates the "ASC OFF" indicator and the TCL/ASC work indicator for three seconds after the ignition switch is turned "ON" position for bulb check.

TCL/ASC-ECU terminal 38 is grounded every time the ASC OFF switch is pressed. TCL/ASC-ECU monitors this operation state and turns the ASC ON or OFF.