Geely EC718 2009 Workshop Manual page 99

Engine
The vehicle speed sensor is installed in the front transmission
case, connected with differential speed sensor drive gear.
Speed sensor is a Hall-style. The main relay controlled by ECM
provides the sensor working power. When the vehicle is
driving, the sensor output is a rectangular pulse signal. Sensor
signals pass through ECM harness connector EN01 terminal
No.57 to ECM. DTC code P0501 will be recorded when there
is a sensor or wiring malfunction.
8. Pre-Catalytic Heated Oxygen Sensor (HO
Pre-Catalytic oxygen sensor is installed in the exhaust
manifold, the three-way catalytic converter front-end, detecting
the oxygen content of exhaust gas and sending ECM the
indirect mixture concentration. ECM adjusts fuel injection pulse
width, to make sure that the mixture ratio is close to the
theoretical value of about 14.7. Oxygen sensor has a sensing
element, which is a porous ceramic tube, the outer wall
surrounded by the engine exhaust and inside connecting to the
atmosphere. Sensing ceramic wall is a solid electrolyte
containing an electric heating tube. When the sensor ceramic
tube temperature reaches 350°C (662 ºF), it has a solid
electrolyte properties. Oxygen sensors work by converting
ceramic oxygen ion concentration difference between inside
and outside into a voltage signal output. The output voltage
level is due to movement caused internal electronic ceramic
tubes. If the mixture is rich, then the ceramic oxygen ion
concentration difference between inside and outside is high,
electrical potential difference is high, a large number of oxygen
ions move from the inside to the outside, the output voltage is
high (close to 800mV). If the mixture is lean, then the ceramic
oxygen ion concentration difference between inside and
outside is low, electrical potential difference is low, only a small
amount of oxygen ions move from inside to outside, the output
voltage is low (close to 200mV). Signal voltage suddenly
changes near the theoretical Air-Fuel ratio (λ=1). Sensor
signals pass through ECM harness connector EN01 terminal
No.45 to ECM. DTC code P0030, P0031, P0032, P0053,
P0130, P0131, P0132, P0133, P0134, P2195 , P2196 will be
recorded when there is a sensor, wire or circuit malfunction.
9. Post-Catalytic Heated Oxygen Sensor (HO
Post-Catalytic oxygen sensor is installed on the three-way
catalytic converter rear end. Its working principle is the same
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as the Pre-Catalytic oxygen sensor. If the three-way catalytic
converter is working properly, fuel control system is in close-
loop control, the sensor output voltage is stable at 0.45V.
Sensor signals pass through ECM harness connector EN01
terminal No.29 to ECM. DTC code P0036, P0037, P0038,
P0054, P0136, P0137, P0138, P0140, P2270, P2271 will be
recorded if there is a sensor, signal or circuit malfunction. DTC
code P0420 will be recorded if the Post-Catalytic oxygen
sensor detects that three-way catalytic converter is not working
properly.
10. Air-Conditioning Pressure Switch
Air-Conditioning pressure switch is installed in the Air-
Conditioning high pressure side pipeline, mainly for Air-
FE02-5129b
Conditioning system control. ECM command the compressor
control relay only when correct signal is received, so that the
electromagnetic compressor clutch pull-in. Switching signals
pass through ECM harness connector EN01 terminal No.10,
44 to ECM. DTC code will not be recorded when there is a
switch or circuit malfunction.
11. Power Steering Switch
Power steering switch is installed on the power steering pump.
When the steering wheel is operated, power steering pump oil
pressure changes due to increased power steering pump load.
If at this point, the engine is in idle state, it will cause the engine
idle fluctuate. In order to make the engine run smooth, after
ECM receives the signal, it will increase the engine's torque. A
typical way is to increase the fuel injection amount. Switching
signals pass through ECM harness connector EN01 terminal
No.12 to ECM. DTC code will not be recorded when there is a
switch or circuit malfunction.
Control System JL4G18-D
EC718/EC718RV EC715/EC715RV 10/2009
2-17
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