Chery A21 2005, Service Manual, Page: 265 / 475

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.
Sta rt
difficultly
（ Remove the
plug ） Set the multimeter at the ohm
shift, the two pens connect to the 1st 、
2nd pin of sensor respectively, the
rating resistance is 2.5k
Ω± 5% when it
is 20 ℃ . The other temperatures please
refer to table 8-1.
:
Fault descrip tion
Troubleshoot ：
can not accelerate well
inds of f luid such as fuel 、 coolant 、 brake fluid 、
water contact to sensor for long time wil result in the erode of sensor.
Remove the plug Set the multimeter to the ohm position,
connecting the two pens to the 1st 、 2nd and 1st 、 3rd pin respectively, and the resistance
in normal temperature should be more than 1M Ω . Set the multimeter at the mV position,
and knock the knock sensor with a hammer gently, then there will be voltage signal output .
（ ）
Fault description
Troubleshoot
：
Fault analysis ：
:
It
Several k
The oxygen sensor is used to detect th e content of oxygen in th e exhaust,the
transmits a signal to ECU, according to the in formation ECU wi ll make t he fuel closed
loop control so that the engine can work in th e best Condition, and mak e the CO, HC,
NOx comp ound tran sformed and depurated mostly by the three-way catalytic converter .
（ 5 ） Knock sensor
There ar e 3 pins on the sensor , the 1st 、
2nd pin connec t to the 19th 、 20th pi n of ECU;
the 3 rd pin con nect to screen.
ECU
19
20
Figure9-9 Knock sensor and its c ircuit diagram
（ 6 ） Coolant temperature sensor
ECU
17
39
1 2
Figu re9-10 Coolant temperature sensor and its circuit
（ 7 ） Oxygen sensor
Figure9-11 Oxygen sensor and its circuit
The knock sensor supply engine knock information to ECU, and control the knock.
Knock sens or
Knock s ensor
Co olant temperature sensor
Front oxygen sensor
P/Br
2
3
1
4
1
18
Front Oxygen Sensor
Rear Oxygen Sensor
G/B
EC U
Main relay
Rear oxygen sensor
Coolant
tempe rature
sen sor
17
Table 8-1
-10
20
80
8.62 … 10.28
2.37 … 2.63
0.299 … 0.345
（℃）
（ k Ω ）
Temperature
Resis tance
There are 4 pins on this oxygen senso r
No.1 c onnect to h eating power positive （ white ）
No.2 c onnects to heating po wer negative （ white ）
No.3 c onnects to signal neg ative （ gra y ）
No.4 c onnects to signal pos itive （ bla ck ）