Minor failure——when a failure shows up, failure code be recorded, but the alarm lamp no light, this type
called minor failure.
In the computer’s failure storage, usually major failure has the priority compare to the minor failure. When
already stored 15 failures, if one major failure appear, then this major failure will instead of one saved minor
failure.
In the system, if appear temporary failure, computer start save the failure code, because detect lamp no light
or it will be extinguished , sometimes driver would not notice , if this failure after engine start 50 times, the
appeared temporary failure not appear again, computer will delete its failure code from memory.
Failure running
The function of failure running means when system get failure, in order to drive car back home or to the
vehicle repair plant , computer invoke back up value parameter order the running.
For example, when cooling water temperature sensor failure , computer take the value parameter of engine
temperature at 80 as fuel inject and ignition control parameter, let the engine keep running. The thing should
℃
notice: when failure running, all relevant system not working in a best state, engine power performance and
economy performance decrease, exhaust pollution may become bad. So, should examine and repair engine as soon
as possible.
After failure eliminated, computer will auto-select actual information parameter, so auto-out of the back up
value , finish the failure running function.
Client opinions
When failure car enter into the maintenance depot , depot people should inquire opinions from client, in
order to find the failure source fast. First should get know the situation, condition, how and whether be
examined ,something about failure when failure happened. So, must give audience to client’s description about
failure , though the description may not integrity or be misconstrued , or maybe self-contradiction, but it often get
the key of the problem. The best way is
：
after listen client’s first opinion , think for a moment, do a first step
diagnosis, then ask some relevant questions for helping make sure or deny first diagnosis’ conclusion. Meanwhile
let client fill “ client questionary” . This blank content is about failure record of engine microcomputer control
system , with diagnose test result together institute the basis of failure source.
Visual measurement
The purpose of visual measurement is for eliminate general failure element before the further careful test and
diagnosis. The content of visual measurement includes:
(1) Take down air cleaner, check filter element and whether has dirty, impurity or other pollutants around ,
must change it in time.
(2) Check the vacuum tube whether broken, aging, or squeeze damaged; check the tube passed path and
tie-in whether correct.
(3) Check the connection situation of wire bundle of microcomputer control system.
a. electric coupler of sensor or actuator is fine.
b. coupler of wiring hamess whether loose or disconnect.
c. electrical wire whether has rupture or disconnection situation.
d. electrical coupler whether splicing in a proper position.
e. Whether wires has frazzle or line to line short circuit situation.
f. Whether electrical coupler’s plug and socket has corrosion.
(4) Check every sensor and actuator whether has obvious damage.
(5) Run engine and check enter/exhaust manifold lambda sensor whether has leakage.
(6) Do the necessary elimination to the failure, and reinstall new air cleaner.
