Antilock Brakes / Traction Control Systems: Description and Operation

SYSTEM DESCRIPTION





Functions
VDC
^ In addition to the TCS/ABS function, the driver steering amount and brake operation amount are detected from steering angle sensor and pressure sensor, and the vehicle's driving status (amount of under steering / over steering) is determined from information from G sensor, wheel sensor, etc., and this information is used to improve vehicle stability by controlling the braking and engine power to all four wheels.
^ SLIP indicator lamp flashes to inform the driver of VDC operation.
^ During VDC operation, body and brake pedal lightly vibrate and mechanical noises may be heard. This is normal.
^ ABS warning lamp, VDC OFF indicator lamp, and SLIP indicator lamp might turn on when vehicle is subject to strong shaking or large vibration, such as when vehicle is on a turn table, a ship or a steep slope such as bank while engine is running. In this case, restart engine on a normal road, and if ABS warning lamp, VDC OFF indicator lamp, and SLIP indicator lamp turn off, there is no malfunction.

TCS
^ The wheel spin of the drive wheels is detected by ABS actuator and electric unit (control unit) from the wheel speed signals from four wheels, so if wheel spin occurs, drive wheel right and left brake fluid pressure control and engine fuel cut are performed while throttle value is restricted to reduce the engine torque and decrease the amount of wheel spin. In addition, the degree throttle is opened is controlled to achieve the optimum engine torque.
^ Depending on road circumstances, the driver may have a sluggish feel. This is normal, because the optimum traction has the highest priority under TCS operation.
^ TCS may be activated any time vehicle suddenly accelerates, suddenly down/up shifts, or is driven on a road with a varying surface friction coefficient.
^ During TCS operation, it informs a driver of system operation by flashing SLIP indicator lamp.

ABS
^ The Anti-Lock Brake System is a function that detects wheel revolution while braking, and it improves handling stability during sudden braking by electrically preventing 4 wheel lock. Maneuverability is also improved for avoiding obstacles.
^ If the electrical system malfunctions, then the fail-safe function starts, the ABS becomes inoperative, and ABS warning lamp turns on.
^ Electrical system diagnosis by CONSULT-II is available.
^ During ABS operation, brake pedal lightly vibrates and a mechanical noise may be heard. This is normal.
^ When starting engine, or just after starting vehicle, brake pedal may vibrate or motor operating noises may be heard from engine compartment. This is a normal status of operation check.
^ Stopping distance may be longer than that of vehicles without ABS when vehicle drives on rough, gravel, or snow-covered (fresh, deep snow)roads.

EBD
^ The Electronic Brake Distribution is a function that detects subtle slippages between front and rear wheels during braking, and it improves handling stability by electronically controlling the brake fluid pressure which results in reduced rear wheel slippage.
^ In case of electrical system malfunction, the fail-safe function is activated, EBD and ABS becomes inoperative, and ABS warning lamp and brake warning lamp returned.
^ Electrical system diagnosis by CONSULT-II is available.
^ During EBD operation, brake pedal lightly vibrates and a mechanical noise may be heard. This is normal.
^ When starting engine, or just after starting vehicle, brake pedal may vibrate or motor operating noises may be heard from engine compartment. This is a normal status of operation check.
^ Stopping distance may be longer than that of vehicles without EBD when vehicle drives on rough, gravel, or snow-covered (fresh, deep snow)roads.

Fail-Safe Function
VDC / TCS SYSTEM
In case of malfunction in the VDC/TCS system, VDC OFF indicator lamp and SLIP indicator lamp are turned on, and the condition of vehicle is the same as the condition of vehicles without VDC/TCS system. In case of malfunction in the VDC/TCS system, the ABS control continues to operate normally without VDC/TCS control.

CAUTION: If the fail-safe function is activated, then perform the self-diagnosis for VDC/TCS/ABS control system. CONSULT-II / Self-Diagnosis

ABS, EBD SYSTEM
In case of electrical malfunctions with the ABS, ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp will turn on. In case of electrical malfunctions with the EBD, brake warning lamp, ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp will turn on. Simultaneously, the VDC/TCS/ABS become one of the following conditions of the fail-safe function.
^ For malfunction of ABS, only the EBD is activated and the condition of vehicle is the same condition of vehicles without TCS/ABS system.

NOTE: ABS self-diagnosis sound may be heard. That is a normal condition because a self-diagnosis for Ignition switch ON and The first starting are being performed.

^ For malfunction of EBD, EBD and ABS become inoperative, and the condition of vehicle is the same as the condition of vehicles without TCS/ABS, EBD system.





CAN Communication
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability Many electronic control units are equipped onto a vehicle, and each control unit shares information and kinks with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.