Knock Sensor - Chery A21 2005 Service Manual

CHERY·A21 SERVICE MANUAL
(Disassemble
multimeter at ohm shift and contact the No.1
and No. 2 pin of the sensor by its two meter
pens. When it is 20 Rated
2.5kΩ±5%. The other temperature can get
reference from above chart.

3.3 KNOCK SENSOR

1)Exterior drawing and pin
This sensor has three pins; No.1 and No.2 pin
connect with ECU, and No. 3 pin connects with
shield.
2)Purpose: This sensor provides engine
knock information to ECU, and carries
out knock control.
3)Installation position
There is a hole in the middle of knock sensor,
and the sensor is assembled on the block
between No.2 and No.3 cylinder head. For the
aluminum alloy block, using long bolt with
30mm long; for the casting iron, using 25mm
long bolt. And the moment is 20±5Nm.
4)Working principle
Knock sensor is a kind of vibrating acceleration
sensor and is assembled on cylinder block. The
sense organ of the sensor is a piezoelectric
element. The vibration of cylinder block is
transferred to piezoelectric crystal by mass
block inside of sensor. The piezoelectricity
crystalloid gets pressure from mass block
vibration, producing voltage on two polar and
transferring vibration signals to voltage signal
and output it. Because the frequency of knock
vibration signal is much higher than the normal
engine vibration signal, the ECU can separate
the signal into knock signal and non knock
signal.
5)Normal working temperature: -40--130℃
6)Malfunction phenomenon and diagnosis
method
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the joint)leave the
℃
the resistance is
digital
Chart 3-4 Exterior drawing of knock
15
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ENGINE EFI SYSTEM
sensor
Knock sensor
Chart 3-5 circuit diagram of knock
sensor