Introduction
The engine has an ECM to control major systems such as fuel
injection control, fuel injection timing control, glow control
system, etc. The ECM accepts input signals from sensors and
instantly drive the electronic fuel injection pump use the data to
based on current ambient conditions. It is essential that both
input and output signals are correct and stable. At the same time,
it is important that there are no problems such as vacuum leaks,
or other problems with the engine.
It is much more difficult to diagnose a problem that occurs inter-
mittently rather than catastrophically. Most intermittent problems
are caused by poor electric connections or faulty wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not be sufficient to determine the cause
of the problems. A road test with CONSULT-II or a circuit tester
connected should be performed. Follow the “Work Flow” on the
next page.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The
customer can supply good information about such problems,
especially intermittent ones. Find out what symptoms are present
and under what conditions they occur. A “Diagnostic Worksheet”
like the example on next page should be used.
Start your diagnosis by looking for “conventional” problems first.
This will help troubleshoot driveability problems on a vehicle with
an electronically controlled engine.
SEF858S
SEF233G
SEF234G
TROUBLE DIAGNOSIS — Introduction
CD20T
EC-33