Symptom Chart - Toyota COMPUTER-CONTROLLED SYSTEM Training Manual

SYMPTOM CHART
TROUBLESHOOTING - Symptom Chart
If no malfunction code is output and the problem
cannot be confirmed by a basic inspection, pro-
ceed to this cha rt and pe rf orm troubleshooting .
This is a cha rt of problem symptoms which was
prepared based on the 4A-FE engine (Sep .,
1989)* .
It is meant only to serve as a means of
familiarizing you with basic troubleshooting pro-
cedures, and is by no means complete . For
actual troubleshooting procedures, refer to the
repair manual for the appropriate engine .
*Except for models which are equipped with the
lean mixture sensor .
REFERENCE
1 . The ECU is not included in the list o f
POSSIBLE CAUSES . However, if all other
components and circuits check out okay, it
can be concluded that the ECU is probably
at fault .
2 . Be sure to also check the wiring harness
and connectors when checking the parts
themselves .
3 . One reason why some problems may not
be detected by the diagnostic system
even when the symptoms do recur is that
they may have occurred outside the
diagnostic system's range of abnormality
detection or the problem not covered by
the diagnostic system may have occurred .
(See page 132 . )
SYMPTOM
POSSIBLE CAUS E
SYSTEM COMPONENT PART TYPE OF TROUBLE
Power su l s stem
Ignition switch Poor contact
pp y y
EFI main relay Won't go o n
Circuit opening relay
Won't go o n
Fuel pump Won't operate
Fuel system Injectors Won't inject
Pressure regulator Fuel pressure too low
Engine does No initial Fuel filter, fuel line Clogge d
not sta
rt
combustion
Cold sta
rt
s stem
Cold sta
rt
injector Won't inject
y
Sta
rt
injector time SW
Won't go on, stays o n
Ignite r
Ignition system Ignition coil No sparkin g
Distributo r
Electronic contro l
system
Distributo r
( G and NE signals)
G and NE signals no t
output
154