Chery Fora (Elara A520). Manual — part 147

CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM

27

causticity liquid to wash it; 3, avoid it from
distorting by outside force.

Simple measurement method: connect fuel
pressure gauge at fuel intake pipe, start the
engine and make the engine running at idle speed;
check the fuel pressure around 350kPa or not;
step on the gas until the engine speed to
2500rpm,and observe if the fuel pressure at
around 350kPa.

3.13 ELECTRONIC THROTTLE VALVE AND

ACCELERATOR

1)Exterior drawing and pin

l Accelerator pin definition

Pin No.1 and No.2 is the anode of the 5V
reference voltage

Pin No.3 and No.5 is the cathode of 5V reference
voltage

Pin No. 4 and No. 6 is output voltage signal

l Electronic throttle valve pin definition

Pin No. 1 is motor anode.

Pin No. 2 is potentiometer anode.

Pin No. 3 is potentiometer cathode.

Pin No. 4 is motor cathode.

Pin No. 5 is signal output 1.

Pin No. 5 is signal output 2.

2)Installation position: Electronic throttle valve:
front end of intake manifold; accelerator: driver
cockpit.

3)Working principle: The engine on time torque
requirement was transferred from accelerator to ECU,
and ECU sends impulse electronic signal to electronic
throttle valve according to torque requirement
information; the motor is running and drive throttle
valve to its opening required degrees; this throttle
valve can stay at one fixed position or change to
another position upon required to meet the

Chart 3-25 Circuit Diagram of

Accelerator

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requirement of the engine working conditions
according to the impulse signal frequency and width
of impulse.

3.14 FAN CONTROL

ECU control the fan according to water
temperature of the engine and the requirement
signal and control the fan system delay at the fit
conditions.

1) Conditions for fan running at low speed:

a) Engine coolant temperature between 96

to

℃

102

.

℃

b) There is air conditioner requirement and the

air conditioning compressor begins to work.

2) Conditions for fan running at high speed:

a) Engine coolant temperature sensor broken

b) Engine coolant temperature higher than

102

.

℃

3) Conditions of fan continue to work after the

engine stops working

A) Engine air intake temperature sensor is

broken and delay 60 seconds.

B) Engine coolant temperature sensor is broken

and delay 60 seconds.

C) Engine coolant temperature higher than

100.5℃, high speed delay 60 seconds.

D) Temperature of intake air more than 70.5℃,

delay 60 seconds.

4) Malfunction diagnose

Short circuits from high relay line to power

supply

Short circuits from high-speed relay line to

ground

Open circuits of high-speed relay line

Short circuits from low-speed relay to power

supply

Chart 3-26 Fan control schematic

Power Supply

High-Speed Relay Of Fan

Low-Speed Relay Of Fan

Double-Speed Fan

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Short circuits from low-speed relay line to

ground

Open circuits of low-speed relay line

Engine coolant temperature sensor failure

Engine intake air temperature sensor failure

3.15 AIR CONDITIONER CONTROL

1)Working principle

Switch on the air conditioner and blower; air
conditioner

pressure

is

regular;

evaporator

temperature

sensor

inspect the

right

data;

requirement signal of air conditioner is sending by
these switches to ECU, and ECU controls air
conditioning relay attracting and provide rotating
speed signal to step motor and open the electronic
fan and air conditioning chart to work.

2)Air conditioner control strategy

a) The air condition can be switched on after 5

seconds of the engine starts.

b) Cut off the air conditioner when temperature of

intake air higher than 140.3℃.

c) Cut off air conditioner when the coolant

temperature higher than 114.8℃; resume the air
conditioning control after its lower than 11.8

.

℃

d) Cut off air conditioner when the engine speed is

higher than 6520rpm or lower than 520rpm.

e) Cut off air conditioner when the pressure inside

of air conditioner high pressure pipe is higher
than 20bar and resume the control when the
pressure is lower than 9.5bar.

f) Cut off air conditioner when the evaporator

temperature is lower than 1.5℃; and resume the
control when it is higher than 4.5℃.

g) Cut off air conditioner when the system pressure

is lower than 8.04V; consume the control when
it is higher than 10.01V.

3) Malfunction diagnosis

Air Conditioner Compressor Clutch

Request

Signal

Form

Air

Conditioner

Power Supply

Chart 3-27 Air conditioner control

schematic

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Blower circuit malfunction (fuse is burnt, relay
circuit is open circuit or short circuit)

Irregular pressure of air conditioner (much higher of
the high voltage or the much lower of the low
voltage)

Malfunction of evaporator temperature sensor

Air conditioner relay circuit is failure (short circuit
to ground, short circuit to power supply, open
circuit).

4 ME7 SYSTEM TEST AND REPAIR ACCORDING TO TDC

Explanation:

1. When it is confirmed that malfunction is steady we can carry out the test and repair as

below, otherwise this will cause wrong diagnosis.

2. There is multimeter mentioned below, it is referred to digital multimeter; prohibit to use

finger multimeter check the EFI system.

3. Check and repair the vehicle with anti theft system please re-program the replaced ECU

when there is the occasion of changing the ECU at “flow up steps”.

4. In this items when the TDC of P0171、P0172、P0335、P0336、P1651 existing, the engine

trouble light will not light on.

5. If it shows much lower of the voltage in some circuit in DTC explanation, it refers to

perhaps there is ground short circuit inside of this circuit; If it shows much higher of the
voltage in some circuit in DTC explanation, it refers to perhaps there is power supply
short circuit inside of this circuit; If it shows circuit failure in DTC explanation, it refers
to perhaps there is open circuit or multi circuit malfunction inside of this circuit.

Diagnosis help: 1. DTC can not be deleted; it is steady failure; if it is occasional failure,

check if it is because of the loosening of cable joint.

2. Check according to the above steps and find noting wrong;

3. During check and repair pay attention that the influence of vehicle

maintenance, cylinder pressure and mechanical ignition timing to
the system;

4. Change ECU and test it. If the DTC can be deleted, the malfunction

is inside of ECU; if the DTC can not be deleted, change back to the
original ECU and check it again according to above items.

4.1 ENGINE DTC (DIAGNOSTIC TROUBLE CODE) LIST

DTC

Definition

DTC

Definition