Mazda Training manual — part 99

Dynamic Driving Safety Systems

DSC

•

The DSC counteracts this tendency by applying brake force to one or more wheels (in
this case to the inside rear wheel). Thus a momentum is built up, overcoming the
tendency of the vehicle to continue in a wider circle than intended, as shown in the
illustration below.

L2003_02033

1

Direction of travel with DSC intervention

3

Counteracting yaw moment

2

Direction of travel without DSC
intervention

4

Brake force applied

During DSC Control

•

The brake force is applied in three ways:

–

Pressure increase mode

–

Pressure hold mode

–

Pressure reduction mode

•

These modes will be explained on the following pages. The sample is for a vehicle that is
oversteering during a left turn.

Curriculum Training

02-55

DSC

Dynamic Driving Safety Systems

Pressure Increase Mode

•

Based on the input signals, the stored map values and internal calculations, the CM
recognizes that the vehicle is about to oversteer during a left turn. The CM decides
whether it is necessary to actuate the brake system and/or to reduce the engine torque.
The following steps explain how the vehicle is kept on the track by activating the brake
system.

NOTE: If the CM decides that the engine torque has to be reduced, it sends a corresponding

signal to the PCM. The PCM then reduces the engine torque by cutting the fuel off,
changing ignition timing and/or by closing the throttle valve (only on vehicles with
electronic throttle valve).

•

When the CM decides that it is necessary to apply brake force to the outer front wheel to
keep the vehicle under the driver’s control, it actuates the traction control solenoid valve
in the brake circuit for the RF and LR wheel. This is done to separate the brake circuit
from the brake master cylinder and to enable the pump to build up pressure in the
corresponding brake circuit.

•

To make sure the DSC operation for the RF wheel does not affect the LR wheel, the CM
activates the LR inlet solenoid valve.

•

The stability control solenoid valve for the RF and LR wheel is actuated and opens a
channel to supply a sufficient amount of brake fluid to the high-pressure pump.

•

The pump motor is switched on, pressure in the RF brake circuit is built up, and brake
force is applied to the wheel. This counteracts the undesired yaw force neutralising the
oversteer tendency, allowing the driver to maintain control.

LF-RR

OFF (open)

RF-LR

ON (closed)

LF-RR

OFF (closed)

RF-LR

ON (open)

LF
RF
LR

ON (closed)

RR

OFF (open)

LF
RF
LR
RR

Pump motor

ON (operating)

L2003_T02016

Traction control solenoid valve

Inlet solenoid valve

Outlet solenoid valve

OFF (closed)

Stability control solenoid valve

OFF (open)

02-56 Curriculum

Training

Dynamic Driving Safety Systems

DSC

L2003_02034

1

Master cylinder

8

Outlet solenoid valve

2

DSC HU/CM

9

Brake calliper LR

3

Damper chamber

10

Brake calliper RF

4

Pump motor

11

Flow control valve

5

Pump

12

Stability control solenoid valve

6

Reservoir

13

Traction control solenoid valve

7

Inlet solenoid valve

14

Brake fluid pressure sensor

Curriculum Training

02-57

DSC

Dynamic Driving Safety Systems

Pressure Hold Mode

•

After the appropriate pressure has been built up, the DSC switches to the pressure hold
mode and deactivates the high-pressure pump. The RF-LR traction control solenoid
valve remains actuated, while the RF-LR stability control solenoid valve closes, because
it is deactivated by the CM. In addition, the RF inlet solenoid valve is activated. The LR
inlet solenoid valve remains closed during the entire process.

LF-RR

OFF (open)

RF-LR

ON (closed)

LF-RR

OFF (closed)

RF-LR

OFF (closed)

LF

OFF (open)

RF
LR
RR

OFF (open)

LF
RF
LR
RR

Pump motor

OFF (stopped)

L2003_T02017

Traction control solenoid valve

Inlet solenoid valve

Outlet solenoid valve

OFF (closed)

Stability control solenoid valve

ON (closed)

02-58 Curriculum

Training