Chery Tiggo 5 (T21). Manual - part 268

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5

25

1. General Brake Operating Condition

For vehicles equipped with ABS, if brake pressure applied to wheels is not enough to lock the wheels, the 
oil pressure generated by master cylinder will be transmitted to the wheel cylinder through normal open 
valve, producing regular braking effect. When it is not necessary to continue braking, and if the driver 
reduces the pressure to brake pedal, the brake fluid of each wheel returns to master cylinder and the brake 
pressure decreases.

Description

Definition

Description

Definition

MC1

Brake Master Cylinder Circuit 1

LPA

Low Pressure Accumulator

MC2

Brake Master Cylinder Circuit 2

FL

Front Left Wheel

EME

Return Pump

RR

Rear Right Wheel

NO

Normal Open (Solenoid Valve)

RL

Rear Left Wheel

NC

Normal Close (Solenoid Valve)

FR

Front Right Wheel

Solenoid Valve

Powered Condition

Solenoid Valve Condition

Normal Open Valve

OFF

OPEN

Normal Close Valve

OFF

CLOSE

FL

RR

LPA

LPA

FR

NC

NC

NC

NO

NO

NO

NO

RL

NC

EME

MC1

MC2

RT21250030

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2. ABS Operating (Relief) Condition

For vehicles equipped with ABS, if brake pressure is applied excessively, the friction coefficient between 
wheels and road will decrease, and the wheels will be decelerated earlier than vehicle, which could cause 
the wheels to lock first. In this case, the ABS control module transmits command that reduces the wheel 
pressure to hydraulic control module. In other words, the normal open valve cuts off oil passage and the oil 
passage of normal close valve is open, in order to reduce the wheel cylinder pressure. At this time, the 
brake fluid drained from wheel cylinder is temporarily stored in the low pressure accumulator. Then, the 
brake fluid stored in low pressure accumulator returns to the master cylinder with the rotation of motor.

Solenoid Valve

Powered Condition

Solenoid Valve Condition

Normal Open Valve

ON

CLOSE

Normal Close Valve

ON

OPEN

FL

RR

LPA

LPA

FR

NC

NC

NC

NO

NO

NO

NO

RL

NC

EME

MC1

MC2

RT21250040

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3. ABS Operating (Maintaining) Condition

When appropriate pressure is applied to the wheel cylinder, ABS system enters maintaining pressure 
state. In other words, the normal open valve cuts off oil passage and the normal close valve also cuts off 
the oil passage, the wheel cylinder pressure is maintained.

Solenoid Valve

Powered Condition

Solenoid Valve Condition

Normal Open Valve

ON

CLOSE

Normal Close Valve

OFF

CLOSE

FL

RR

LPA

LPA

FR

NC

NC

NC

NO

NO

NO

NO

RL

NC

EME

MC1

MC2

RT21250050

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4. ABS Operating (Boost) Condition

When ABS operates under relief pressure condition, if brake fluid is drained excessively or friction 
coefficient between wheel and road surface increases, it needs to increase each wheel pressure. In this 
case, the ABS control module transmits command that increases wheel pressure to the hydraulic control 
module. In other words, the normal open valve opens oil passage and the normal close valve cuts off oil 
passage, in order to increase the wheel cylinder pressure. Brake fluid stored in the low pressure 
accumulator is supplied to each wheel cylinder through the master cylinder and normal open valve.

ABS system operates circularly under relief, maintaining and boost pressure conditions until vehicle is 
completely stopped, so the vehicle braking and steering performance will be guaranteed.

Solenoid Valve

Powered Condition

Solenoid Valve Condition

Normal Open Valve

OFF

OPEN

Normal Close Valve

OFF

CLOSE

FL

RR

LPA

LPA

FR

NC

NC

NC

NO

NO

NO

NO

RL

NC

EME

MC1

MC2

RT21250060