Page 73 - Foton Workshop Manual - Auman EST-M

Diagnosis - Diagnosis-fault diagnosis of electronic and electrical parts DI - 19

Diagnosis system IN
1. System overview
ECU integrated diagnostic system belongs to the electronic control engine management system. It monitors DI
the communication of input/output signal and control unit via its self-testing unit.

Electronic online fault diagnostic system is a control unit to perform self-monitoring via “intelligent software”,
EG
i.e. check, store and diagnose the faults. Any auxiliary device isn’t required for the online fault diagnosis.

While the vehicle is running, it shall monitor the input and output signals of logic module, whole system and
its running faults and disturbance. All the monitored faults can be stored into the inner fault storage area of TR
ECU. These faults shall be stored as fault codes, which can be read out via the fault diagnostic interface of
diagnostic unit. AX
2. Storage of information

a. After each fault occurs and is confirmed by the system, it shall be stored into nonvolatile area of data
FR
memory as single state code. The fault code describes the fault type (e.g. short circuit, broken circuit,
distortion and over limit).
b. Each fault code has additional information, i.e. state parameters of faulted engine, including load value, ST
engine speed, fuel pressure &speed and cooling fluid temperature, etc.
3. Error handling
BR
a. If an error occurs at a certain time, the signal channel will classify it. The system will always use the valid

value of final check until the error classification ends. One standby function will be performed during the
BW
error classification (e.g. each actuator of system will be controlled as per the control parameters at cooling
fluid temperature T=90℃).
b. Upon detecting the fault, the limping policy will be also performed in addition to alternate value (e.g. EL
engine power output and speed limit). This policy will provide the following assistance:

● To ensure the driving safety.

● To avoid the damages corresponding to faults.

● To make the exhaust reduced.

● Timely repair.
4. Failure lamp
a. The fault indicator lamp of instrument panel shall be
controlled as internal calibration of ECU. It will always go

on when any fault occurs.

b. When the system has no faults.
● Upon turning the ignition switch to “ON”, the engine will
perform its self-diagnosis, and its fault lamp will go out
after it’s on for 2s.

● Upon turning the ignition switch to “LOCK” position, the

fault indicator lamp will go out immediately.
● If the fault disappears (e.g. poor contact), the fault
data will be still stored in the fault memory, and the fault
indicator lamp will go out after 3 non-fault cycles.
c.When the system has any fault

● the fault lamp will be always on after turning the ignition
switch to “ON”.
● the fault lamp will go out automatically in the next
operating cycle after the faults of electric injection system
disappear.

DI-019