Mazda Training manual — part 103

Dynamic Driving Safety Systems

DSC

Diagnostics

•

The DSC OFF indicator light can be checked as follows:

–

Visually inspecting the light after switching the ignition on

–

Using the input/output check mode for the IC

–

Monitoring the corresponding PID (see below)

PID

Definition

Unit/Condition

TRAC_OFF

DSC OFF indicator light

ON/OFF

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DSC OFF Switch

•

The DSC OFF switch is located in the dashboard. With this momentary switch, the driver
can disable the DSC operation in case the vehicle is stuck, and spinning the wheels may
help to free the vehicle.

•

Whenever the DSC is switched off, the DSC OFF indicator light in the IC will be
illuminated. The DSC will automatically be switched on again, after switching the ignition
off and on.

NOTE: Current Mazda vehicles with DSC do not feature a special switch for disabling the

TCS function. The TCS is automatically disabled / enabled together with the DSC.

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1

DSC OFF switch

Curriculum Training

02-71

DSC

Dynamic Driving Safety Systems

Diagnostics

•

The DSC Off switch can be checked as follows:

–

Visually inspecting the DSC OFF indicator light while switching the DSC on and off

–

Reading out DTCs

–

Measuring voltage signals and resistance

–

Monitoring the corresponding PIDs (see below)

PID

Definition

Unit/Condition

TCYC_SW

DSC Off switch

Pressed / Not pressed

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NOTE: Depending on the vehicle, a DTC might be stored in the DSC HU/CM when the DSC

Off switch is pressed and held for more than approx. 10 s. In this case, the DSC is
re-enabled and cannot be disabled again, unless the ignition is switched off and on
again.

02-72 Curriculum

Training

Dynamic Driving Safety Systems

EBA

Emergency Brake Assist

•

If the driver does not press the brake pedal hard enough in emgergency braking
situations, the brake pressure is increased by the EBA (Emergency Brake Assist). The
advantage is a significantly reduced braking distance. The EBA is available only in
combination with ABS.

•

The EBA is automatically activated if the driver presses the brake pedal very fast, as he
usually automatically does in an emergency situation. Once the system is activated, it
applies full brake pressure to all wheels regardless of pedal pressure applied by the
driver. Of course, the ABS ensures that no wheels lock-up and that the vehicle remains
fully steerable.

•

Mazda uses two different types of EBA:

–

The electronically operated EBA, that is installed on Mazda6

–

The mechanical operated EBA, that is installed on Mazda2, Mazda3 and Mazda5

Electronic EBA

•

The electronic EBA system is based on the DSC function, but applies brake pressure
simultaneously for each wheel.

•

It uses the built-in brake fluid pressure sensor to monitor the speed at which the brake
fluid pressure increases when the brake pedal is pressed. If the brake pedal is pressed
faster than a specified value, the brake fluid pressure increases very fast, and the DSC
HU/CM consequently decides to initiate EBA operation.

•

When the EBA operation is initiated, the DSC HU/CM increases the brake fluid pressure
in the same way as it does for the TCS / DSC operation during pressure increase mode.

NOTE: The vehicle must be driven faster than approx. 17 km/h to initiate the electronic EBA.

Once initiated, it is disabled when the vehicle speed is less than approx. 5 km/h or
when the driver releases the brake pedal.

Curriculum Training

02-73

EBA

Dynamic Driving Safety Systems

Mechanical EBA

•

The mechanical EBA is a function incorporated into the brake booster. It detects
mechanically how fast the brake pedal is pressed. If it is pressed faster than a specified
value, the system uses the brake booster to apply full brake fluid pressure.

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1

Cross-sectional view

4

During normal braking

2 Output

characteristics

5 Operation characteristics (varies

according to pedal force)

3

During brake assist operation

02-74 Curriculum

Training