TCS Control

TCS CONTROL
a. Engine Control
There are two types of engine control (torque down), one is focused on stability (normal control) and the other is focused on acceleration (acceleration control). An integrated control unit is formed with the ABS (ABS/TCS C/M), which monitors wheel speed and, when the engine control varying threshold value is exceeded, starts TCS control, sending a slip signal to the engine control module. The signal is received by the engine control module, where the target output torque value is calculated according to patterns established inside the engine control module. The cut number of the fuel injection cylinder is then determined so that the torque value is offset, and the engine output is reduced.

The calculation of the target output torque value is modified for normal control and control focused on acceleration. Moreover, once the wheel slipping is restrained, TCS control is terminated and conditions return to normal 4-cylinder operation.

- Normal control
The ABS/TCS C/M calculates the slip conditions of the driving wheels and generates a TCS signal based on a large amount of slipping (slipping ease). With this signal, the calculated value inside the engine control module is gradually reduced and the engine injection cut cylinder number is increased, resulting in reduced engine output and restrained wheel slip due to overtorque.

- Control focused on acceleration
When the slip conditions of the only one driving wheel slips continuously, the calculated value inside the engine control module is gradually returned to its original value. This controls acceleration (below 50 km/h) by causing the cut cylinder number to be reduced and the engine torque to return to its original status.

b. Brake Control
As in the case of engine control, brake control starts when the driving wheel slip exceeds the control varying threshold value.
Once brake control has been initiated, the brake pressure needed for control drives the H/U (Hydraulic control unit) motor pump; brake fluid is then taken from the master cylinder through the suction circuit, and hydraulic pressure is produced. At the same time, the H/U hydraulic circuit solenoid valves TCS1 and TCS2 are operated, switching from the hydraulic circuit to TCS control mode. Solenoid valves FRI and FRO (FR Wheel cylinder control use) and FL and FLO (FL Wheel cylinder control use) then switch over to pressure rise - pressure hold - pressure drop conditions, and the fluid pressure produced by the H/U is applied to the driving wheel brakes, stopping the wheel slip.

Once the wheel slip has been restrained and drops below the wheel speed varying threshold value of the driving wheels, the hydraulic pressure in the wheel cylinders are dropped and the motor pump and solenoid valves stop.
Brake control utilized left-right independent control, so when the wheels on one side slip, brake pressure operates only on that side. Not operate on the other side, where the wheels are gripping, an effect similar to LSD (start/acceleration improvement) is obtained to prevent the wheel torque from dropping.

c. Conditions under Which TCS Control Is Not Exercised (Except in a failure)
Under the following conditions, TCS control is suspended. When this happens, TCS OFF lamp comes on to inform the driver that TCS control is OFF
- When the TCS OFF switch is operated. (During TCS control, operation of the button is ignored to prevent misoperation.)
- When engine control module requires that TCS control be OFF.
- When the results of calculations of the brake estimated temperature determine that a high temperature condition is created. (Stop the TCS control to naturally cool the brake. This will restore the brake to its normal condition.)
- When the brake fluid level is low.
- When the brake pedal is depressed. (In this case, "OFF does not light.)