System Description

Fig. 1 Traction Control System Components:

SYSTEM DESCRIPTION

Traction Control System (TCS), Fig. 1. is used to prevent wheel spin when the car is accelerating on a slippery surface.
The TCS system for automatic transmissions consists of two subsystems, the Electronic Throttle System (ETS) and Automatic Slip Reduction (ASR).
TCS utilizes many of the components in the ABS system. The major addition to the system is the Electronic Throttle System.
Automatic transmission TCS does not have the capability to apply the brakes during wheel spin conditions, however this system does control the operation of the transmission kickdown cable in addition to controlling the throttle butterfly.

SUBSYSTEM DESCRIPTION ELECTRONIC THROTTLE SYSTEM (ETS)

The main purpose of the ETS system is to electronically control the position of the throttle butterfly.
The throttle housing is equipped with an actuating motor for the throttle butterfly, a vacuum unit, a throttle potentiometer and a safety cutout switch. Connected to the accelerator pedal is a pedal sensor with associated solenoid valves and a non-return valve fitted on the bulkhead. For additional safety, a parallel system using a throttle cable is provided, which will take over in the limp-home mode.

Automatic Idling Control (AIC)

The ETS eliminates the need for separate components for Automatic Idling Control (AIC) and load related control over the entire working range of the engine.

Smooth Response To Heavy-Footed Use Of Accelerator

If the driver depresses or releases the accelerator abruptly, the throttle butterfly will be operated in two steps within a period of just a few milliseconds. This allows the car responding smoothly on both acceleration and deceleration.

Integral Cruise Control Function

The ETS system incorporates a cruise control function. Since operation of the cruise control system is based on acceleration control, maximum engine performance is available under all conditions, unlike some previous systems which reverted to basic boost when cruise control was operating.

Intelligent System

The ETS is an intelligent or adaptive system, which means that it adapts itself automatically to changes in air pressure, humidity and variations due to wear in components.
The ETS also incorporates an AIC function for the warm-up phase, governed by time and coolant temperature.
The system continuously processes data from the speedometer, direct ignition system, ABS system, LH system and temperature sensor. It also monitors the position of the throttle butterfly and accelerator.
On the basis of this input data, the ECU controls the actuating motor for the throttle butterfly.

AUTOMATIC SLIP REDUCTION (ASR)
Vehicles with automatic transmissions utilize only the throttle butterfly for traction control. With the addition of a kickdown cable control, the ASR system can be described separately even though ASR is an integral part of the Electronic Throttle System (ETS).
Automatic transmission vehicles with traction control utilize another control unit to assist in operation of the kickdown wire (KDW). This additional ECU is on top of the ETS ECU which is fitting since the ASR ECU and the ETS ECU are basically one control unit.