Chery Tiggo 5 (T21). Service manual — part 268
25–
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
25–
6
25
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
25–
7
25
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
25–
8
25
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
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