Chery A11. Manual — part 171

Maintenance Manual for Chery·Windcloud

MOTOROLA EFI System

Chapter Two: Basic Principle for EFI System Failure Diagnosis

(1). Failure Information Record
Electronic control unit constantly monitors sensors, actuators, relevant circuits, fault
indicating lamp and accumulator voltage, etc. and even electronic control unit itself, and
carries out reliability test on sensor output signal, actuator drive signal and internal signal (for
instance: oxygen closed-loop control, knocking control, idle speed control and accumulator
voltage control). Once a certain link is found failed, or a certian signal value is unreliable,
electronic control unit will make information record of failure immediately in failure
memorizer of RAM. Failure information record will be stored in form of failure code, and
displayed as per sequence of failure occurrence.
Failure, according to frequency of occurrence, can be divided into “constant failure” and
“random failure” (for example: failure caused by temporary wire harness open circuit or
poor contact of socket connector).

(2). Failure Status
If the continuance of an identified failure exceeds the stabilization time stipulated for the first
time, ECU collects it as a stable failure, and stores it as “constant failure”; if such failure
disappears, ECU stores it as “random failure” and “nonexistent”; if such failure is identified
again, then still it is “random failure”, but the “existent” history failure does not impact the
normal use of engine.

(3). Failure Types
Short circuit to power supply anode
Short circuit to on ground
Open circuit (on occasion that input stage has upward pull/downward pull resistor, ECU will
identify the open circuit failure at input port as input port failure of short circuit to power
supply anode or short circuit to ground)
Signal unreliable

(4). Four Types of Failure
Max. failure, signal exceeds upper limit of normal range.
Min. failure, signal exceeds lower limit of normal range.
Signal failure, no signal.
Illogical failure, signal exists, but illogical.

(5). Limp Home
For some important failure identified, whose duration exceeds stabilization time stipulated,
ECU will adopt software countermeasure as appropriate to maintain operation of engine and
avoid breaking down of vehicle on the road.

(6). Failure Alarm
MOTOROLA EFI system has fault indicating lamp. In case failure occurs with relevant

14

Maintenance Manual for Chery·Windcloud

MOTOROLA EFI System

failure mark being set on some important parts such as ECU, manifold absolute pressure
sensor, throttle position sensor, coolant temperature sensor, knock sensor, oxygen sensor,
phase sensor, injector and two driver stages of idle speed actuator stepper motor, ECU will
alarm by lighting up fault indicating lamp until the said failure mark restores.

(7). Failure Readout
Failure information record can be called up from electronic control unit through scanner, also
it can be read out through the form of flash code output. If failure involves the function of
proportion regulator of fuel/air mixture, the engine shall operate at least 4 minutes to read
failure information record.

ISO 9141-2 Standard diagnostic joint

Connection of Scanner
Engine compartment and fire wall are equipped with diagnostic interfaces, and the failure
code installed in engine RAM is readable through application of scanner, and data flow
during the operational process of engine is also readible through the scanner, which is
favourable for troubleshooting of engine system.

Earth signal wire of engine diagnostic interface and ground of diagnostic interface, in this
way, engine failure code can be read out through flash frequency of fault light.

(8). Clearance of Failure Information Record

After elimination of failure, failure information record in memorizer shall be cleared.
When ignition is switched on, in case a failure occurs but dose no continue to the end of
stabilization time, the failure information will not be recorded.
 After a certain times of successful startup of engine, the failure code will be removed
automatically.
Use scanner to remove failure information record by selecting the command of “Clear failure
memory”.
 Unplug ECU connection or pull out accumulator wires, and clear failure information record
in external RAM.

(9). Failure Location:
Failure information record is obtained via the aforesaid means with only the rough part of
failure occurrence found. For the reason causing a failure information may be electrical

15

Maintenance Manual for Chery·Windcloud

MOTOROLA EFI System

element breakdown (for example: sensor, actuator or ECU); may be wire having open circuit
or short circuit to ground or accumulator anode; and may be even mechanical failure.
Failure is an internal error, its external exhibition is various symptoms. If a symptom is found,
first check with scanner or according to flash code to see if there is any failure information
record, and eliminate relevant failure as per failure information, and then troubleshoot
according to engine symptom.

16

Maintenance Manual for Chery·Windcloud

MOTOROLA EFI System

Engine Failure Code Table

Code Error source

Type of
error

MI
L

Error description

Countermeasure to be adopted

Flash
code

9

Intake pressure sensor

Hi

Lit Excessive intake pressure Replaced with throttle position

signal

2311

0a

Intake pressure sensor

Lo

Lit Too low intake pressure

Replaced with throttle position
signal

3311

0b

Intake pressure sensor

Hi/Lo

Lit Intake pressure out-of-limit Replaced with throttle position

signal

4311

0e Ambient

atmosphere

pressure

Lo

Low ambient atmosphere Use AAP default value

3411

10

Throttle position sensor AZ

Lit Throttle automatic zero

setting failure

Use default value

1121

11

Throttle position sensor Hi

Lit Open circuit occurs in

throttle position sensor

Use default value

2121

12

Throttle position sensor Lo

Lit Short circuit occurs in

throttle position sensor

Use default value

3121

13

Throttle position sensor Hi/Lo

Lit Open/short circuit occurs

in throttle position sensor

Use default value

4121

15 Intake air temperature

sensor

High Too low intake air

temperature

Use default intake air
temperature value

2221

16 Intake air temperature

sensor

Lo

Excessive intake air

temperature

Use default intake air
temperature value

3221

17 Intake air temperature

sensor

Hi/Lo Intake

air

temperature

out-of-limit

Use default intake air
temperature value

4221

19 Coolant temperature

sensor

Hi Lit

Too low coolant
temperature

Use default coolant temperature
value

2321

1a Coolant temperature

sensor

Lo Lit

Excessive coolant
temperature

Use default coolant temperature
value

3231

1b Coolant temperature

sensor

Hi/Lo Lit

Coolant temperature
out-of-limit

Use default coolant temperature
value

4321

1c Oxygen

sensor

MISC Lit Open circuit occurs in

oxygen sensor

Open-loop control

1421

1d Oxygen

sensor

Hi

Lit

Excessive

oxygen

sensor

output voltage signal

Use default oxygen sensor
signal value

2421

1e Oxygen

sensor

Lo

Lit

Excessive

oxygen

sensor

output voltage signal

Use default oxygen sensor
signal value

3421

1f Oxygen

sensor

Hi/Lo Lit Oxygen sensor output

voltage signal out-of-limit

Use default oxygen sensor
signal value

4421

21

Supply voltage

Hi

Lit Excessive supply voltage Use default supply voltage

value

2131

22

Supply voltage

Lo

Lit Too low supply voltage

Use default supply voltage
value

3131

23

Supply voltage

Hi/Lo

Lit Supply voltage out-of-limit Use default supply voltage

value

4131

2c

Crankshaft

position Reg

Lit Normal tooth error

Resynchronization

1431

17