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（5）Knock sensor
The knock sensor supply engine knock information to ECU, and control the knock.
There ar e 3 pins on the sensor , the 1st、
2nd pin connec t to the 19t h、20th pi n of ECU;
the 3 rd pin con nect to scre en.
Figure9- 9 Knock sensor and its c ircuit dia gram
Fault description
：
It
can not accelerate well
Fault analysis：
Several k
inds of f luid such as fuel、 coolant、 brake fluid、
water c ontact to sensor fo r long time wil result in the erode of sensor.
Troubleshoot
:
（
Remove the plug
connecting the two pens to the 1st、2nd and 1st、3rd pin respectively, and the resistance
in normal temperature should be more than 1MΩ. Set the multimeter at the mV position,
and knock the knock sensor with a hammer gently, then there will be voltage signal output .
（6）Coolant te mperature s ensor
The coolant temperature sensor
supply coolant signal to ECU, so as to
enable the start、 idle speed、 ignition
timing and injection impulse width
modify. There are two pins, and they
can exchange to use.
Fault descrip tion
:
Sta rt
difficultly
Troubleshoot：
（ Remove the
Te mp er atu re
plug） Set the multimeter at the ohm
shift, the two pens connect to the 1st、
2nd pin of sensor respectively, the
rating resistance is 2.5kΩ±5% when it
is 20℃. The other temperatures please
Figu re9-10 Coolant tem pe rature sensor and its circuit
refer to table 8-1.
19
Knock sens or
20
ECU
Knock s ensor
）
Set the multimeter to the ohm position,
Co olant temperature sensor
17
Ta ble 8-1
Resis tance
（℃）
（kΩ ）
1
2
39
-10
8.62...10.28
ECU
20
2.37...2.63
C oolant
tempe rature
80
0.299...0.345
sen sor
（7）Oxygen s ensor
The oxygen s ensor is used to detect th e content of oxygen in th e exhaust,the
transmits a signal to ECU, a ccording to the in formation ECU wi ll make t he fuel closed
loop control so that the eng ine can w ork in th e best C ondition, and mak e the CO, HC,
N Ox comp ound tran sformed and depurated mo stly by the three-w ay catalytic converter .
Rear Oxygen Sensor
EC U
1
2
G/B
1
P/Br
18
4
3
Front Oxygen Sensor
There are 4 pins on this oxy gen senso r
No.1 c onnect to h eating power positiv e （white）
No.2 c onnects to heating po wer negat ive （whit e）
No.3 c onnects to signal neg ative（gra y）
No.4 c onnects to signal pos itive （bla ck）
Figure9 -11 Oxygen sensor and its circuit
Main relay
Front oxygen sensor
Rear oxyg en sensor
17
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