SsangYong Stavic / SsangYong Rodius (2005 year). Service manual - part 407

ABS/ESP SYSTEM

STAVIC - 2004.09

11

4K

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

Master cylinder

Primary

circuit

Secondary

circuit

Damping

chamber

Pump

Low pressure

accumulator

Inlet

valve

(FR)

Inlet

valve

(FL)

Low pressure

accumulator

Inlet valve

(all rear

wheel)

Outlet valve

(FR)

Outlet valve

(FL)

Outlet valve
(all rear wheel)

Wheel (FR)

Wheel  (FL)

Wheel (RR)

Wheel (RL)

The vehicle equipped only with the ABS controls the wheel’s braking force using three 3-channel 4-sensor method. The
front wheels that are the primary circuit of the brake system is composed of two wheel speed sensors and two channel
valves system with two inlet valves and two outlet valves. The rear wheels that are the secondary circuit of the brake
system is composed of two wheel speed sensors, one inlet valve and one outlet valve. This system is similar to the one
from the previous model.

5. HYDRAULIC CIRCUIT DIAGRAM

Hydraulic Circuit of ABS

ABS/ESP SYSTEM

STAVIC - 2004.09

12

4K

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

ABS Circuit Per ABS Operation Range

Hydraulic Pressure Circuit when ABS is Not Operating

The hydraulic pressure in the master cylinder increases through the vacuum booster and it is delivered to the wheel via
the normal open inlet valve. At this moment, the normally-closed outlet valve is closed. The speed of the wheel that
hydraulic pressure is delivered reduces gradually .

No Hydraulic Pressure Circuit when ABS is Operating

As hydraulic pressure on each wheel increases, the wheel tends to lock. In order to prevent the wheel from locking, the
hydraulic valve modulator operates the inlet valve control solenoid to close the inlet valve and stop the hydraulic pressure
increases. At this moment, the outlet valve is closed. This procedure helps the wheel to maintain a stable hydraulic
pressure.

Pump

Low pressure

chamber

Inlet valve

Outlet valve

Constant pressure

Pump

Low pressure

chamber

Inlet valve

Outlet valve

ABS/ESP SYSTEM

STAVIC - 2004.09

13

4K

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

Pressure Decreases in the Circuit when ABS is Operating

Even when the hydraulic pressure on each circuit is stable, the wheel can be locked as the wheel speed decreases.
This is when the ABS ECU detects the wheel speed and the vehicle speed and gives the optimized braking without
locking the wheels. In order to prevent from hydraulic pressure increases, the inlet valve is closed and the outlet valve is
opened. Also, the oil is sent to the low pressure changer and the wheel speed increases again. The ABS ECU operates
the pump to circulate the oil in the low pressure chamber to the master cylinder. This may make the driver to feel the
brake pedal vibration and some noises.

Pressure Increases in the Circuit when ABS is Operating

As the wheel speed increases, the inlet valve opens and the wheel’s pressure increases due to the master cylinder
pressure. The oil in the low pressure chamber circulates to the wheel by the pump and the wheel speed decreases as
the hydraulic pressure at wheel increases. This operation continues repetitively until there are no signs that the ECU is
locking the wheels. When the ABS hydraulic pressure control takes place, there may be some vibration and noises at
the brake pedal.

Pump

Low pressure

chamber

Inlet valve

Outlet valve

Pressure decreases

Pump

Low pressure

chamber

Inlet valve

Outlet valve

Pressure increases

ABS/ESP SYSTEM

STAVIC - 2004.09

14

4K

CHANGED BY

EFFECTIVE DATE

AFFECTED VIN

Motor Pump

The motor is operated when ABS is activated. The cam-shaped
output shaft of the motor enables the brake system to receive
and supply the brake fluid during the motor operation.

Valve Body

The cam bushing is installed between plungers and it draws
and discharges the brake fluid.

6. COMPONENTS DESCRIPTION

HECU (Hydraulic & Electronic
Control Unit)

HECU consists of motor pump (1), solenoid valve (2) and ECU
(3).

ECU connector has 47 pins and the number of valves in valve
body is 6 when equipped with only ABS and 12 when equipped
with ESP system.