Geely EC718, EC718RV, EC715, EC715RV. Manual part — 309

6.6 ABS / TCS / EBD / ESP

6.6.1 Specifications
6.6.1.1 Fastener Tightening Specifications

Applications

Model

Specifications

Metric (Nm)

US English (lb-ft)

Wheel Speed Sensor Harness
Connector Bolts

M6 × 18

19-22

14-16.3

ABS Bracket Strengthening
Plate Assembly Nut

M8

23-30

17-22.2

6.6.1.2 Wheel Speed Sensor Technical
Specifications

Wheel Speed Sensor

Description

Sensor Type

Hall-type Speed Sensor

Voltage

4.5-20 V

Signal Current

Low: 7 ± 20% mA, High: 14 ± 20% mA

Gap Between The Signal Plate and The Sensor

Front Axle 1.56 mm (0.06 in) Rear Axle 0.738 mm (0.03 in)

Brake System

ABS / TCS / EBD / ESP

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6.6.2 Description and Operation
6.6.2.1 Description and Operation

This vehicle is equipped with anti-lock braking system (ABS)
and electronic brake-force distribution (EBD) system. In
addition to in the original brake system, the following
components are added:

Hydraulic Electronic Control Unit (HECU):

Note

Between hydraulic electronic control unit installation
bolts and bracket, there are rubber anti-vibration pads,
which are used to avoid the hydraulic electronic control
unit being affected by the vehicle vibration. The hydraulic
electronic control unit can not be disassembled, and
must be replaced as an assembly.

The hydraulic electronic control unit (HECU) controls system
function and detect faults. When the ignition switch is turned
on and there are no anti-lock braking system DTC codes, the
system provides power to the relay, so the battery positive
voltage is provided to the solenoid valve and pump. Hydraulic
electronic control unit (HECU) continuously tests the wheels
status to control wheel slip rate within a certain range so as to
maintain the vehicle stability. Hydraulic control piping uses
diagonal configuration, so that from the brake master cylinder
one channel fluid flows along the left front to right rear wheel,
the other flows from the right front to the left rear wheel. Two
channels are isolated, so that when one brake channel fails or
leaks, the other will make sure the continuous braking ability.
Hydraulic electronic control unit (HECU) includes the following
main components:

–

ABS control module

–

ABS Pump and Relay

–

Inlet Valve, each valve controls one wheel

–

Outlet Valve, each valve controls one wheel

–

Electromagnetic Coil Relay

Wheel Speed Sensor:

Wheel speed sensor is a Hall-type speed sensor. With the
wheels rotating, ABS control module uses the wheel speed
signal to calculate the wheel speed. Wheel speed sensor can
be individually replaced, but the signal plate (Gear) is fitted on
the axle and must be replaced together with the axle.

Brake Lamp Switch:

Press the brake pedal, the brake lamps are lit, while signals are
sent to the ABS brake control module.

ABS Warning Lamp:

Located on the instrument cluster, light to notify the driver the
ABS failure when the following events occurs:

–

ABS control module detects the ABS system malfunction,
the instrument cluster receives a request for lighting the
ABS warning lamp through the CAN bus from the ABS
control module.

–

Instrument cluster carry out self-test in the beginning of
each ignition cycle, the indicator light about 3s.

–

Instrument cluster detects the communication to the ABS
control module is lost.

EBD Warning Lamp:

Located on the instrument cluster, light to notify the driver EBD
failure. When the ABS Warning Lamp is lit, but EBD warning
lamp is not lit, the system will still have EBD function. When the
ABS Warning Lamp and EBD warning lamp are all lit, ABS and
EBD function all fail.

Self-diagnostic Test:

ABS control module performs a self-diagnostic test each time
the ignition switch is turned to on. As long as the ABS is
provided power and in a working status, it monitors the
performance. Once a fault is detected, it will trigger an alarm
until the fault disappears. ABS error code will be stored in
memory until being manually erased.

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ABS / TCS / EBD / ESP

Brake System

6.6.3 System Working Principle
6.6.3.1 System Working Principle

Anti-lock Braking System (ABS) Hydraulic Piping Diagram

AV

EV

FL

RR

RL

FR

AV

M

LPA

EV

AV

EV

AV

EV

FE06-5601b

Orifice

Legend

1. AV-Inlet Solenoid Valve
2. EV-Outlet Solenoid Valve
3. LPA-Low Pressure Accumulator
4. M-Motor
5. FL-Left Front Wheel

6. RR-Right Rear Wheel
7. RL-Left Rear Wheel
8. FR-Right Front Wheel

Anti-lock Braking System (ABS)

In the anti-lock braking period, anti-lock braking system
controls each wheel braking fluid pressure to prevent wheel
slip. Each wheel is equipped with a separate and specific
hydraulic fluid line solenoid valve. Anti-lock braking system can
reduce, maintain or increase brake fluid pressure to each
wheel. However, the anti-lock braking system can not make the
pressure exceed the pressure provided by the brake master
cylinder. During the anti-lock braking, a series of rapid pulse
can be felt on the brake pedal. When the ABS control module

detects the speed sensor input and tries to prevent wheel slip,
each solenoid valve position rapidly changes. ABS pump starts
working, resulting pulse. Pedal pulse only appears during the
anti-lock braking, and disappears during the normal braking or
parking. For vehicles equipped with anti-lock braking system,
apply normal force on the brake pedal can stop the vehicle.
Anti-lock braking system can effectively shorten the braking
distance and maintain the vehicle stability. During the anti-lock
braking, brake system pressure is adjusted in three stages.

Brake System

ABS / TCS / EBD / ESP

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Pressure Maintaining

When the wheel spins, ABS control module closes the inlet
valve and keeps the valve closed and isolated from the system.
It maintains the braking fluid pressure without increasing or
decreasing.

Pressure Decrease

When the wheel spins, ABS control module reduces the
pressure to individual wheels during deceleration. The inlet
valve is closed, while the outlet valve is open. The excess fluid
is stored in the accumulator until the ABS pump returns the fluid
to the master cylinder.

Pressure Increase

When the wheel does not spin, ABS control module gradually
increases the braking pressure to each wheel to reduce wheel
speed. The inlet valve is open, while the outlet valve is closed.
The increased pressure is provided by the brake master
cylinder.

Electronic Brake Force Distribution (EBD)

Each wheel attached ground conditions may be different, then
the ground friction coefficient will be different. During braking,
the vehicle gravity center will change, so the vehicle is prone
to skid when braking, tilt and roll and so forth. EBD's function
is to calculate four tires friction difference as a result of different
adhesion coefficients at the braking moment, then adjust the
hydraulic unit electromagnetic valve. The valve adjusts as the
preset program to match the system power to the friction
(adhesion), ensure vehicle braking smooth and safety. Under
the emergency braking situation, before the ABS action EBD
has balanced each wheel grip, to prevent tail-flick and the
lateral movement. EBD is actually an additional ABS function.
Based on road and load changes, it automatically adjusts the
braking force distribution, improves and the ABS efficiency.

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ABS / TCS / EBD / ESP

Brake System