SYMPTOM SIMULATIO
N
SYMPTOM SIMULATIO
N
The most difficult problems in troubleshooting
are intermittent problems
: that is, problems
about which the customer has a complaint, but
which do not occur or cannot be comfirmed in
the service shop
. Intermittent problems often
include complaints about the "CHECK ENGINE"
lamp going on and off erratically
.
To ensure accurate diagnosis of such problems,
ask the customer to provide as much information
as possible
.
To do this, question the customer closely about
the problem, using the Pre-diagnostic
Questioning Checksheet, then try to reproduce
the problem on the customer's vehicle
.
The symptom simulation methods (applying
vibration, heat, or humidity) described below are
effective ways of reproducing the symptoms for
problems of this nature
.
OBJECTIVE To learn
how to reproduce intermi
tt
ent problems
PREPARATIO
N
APPLICABLE ENGIN
E
1
Terminals have sprea
d
VIBRATION METHOD
: When
vibration seems to be the major cause
.
CONNECTORS
Gently shake the connectors vertically and hori-
zontally and pull on them
:
(a) Are they loose
?
(b) Does the wire harness have enough slack
?
Watch especially for
:
• Dirty terminal
s
• Loose contact due to spreading of terminals
163
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