B71602
Vibrate Slightly
Shake Slightly
Vibrate
Slightly
D25084
Malfunction
--
INTRODUCTION
HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
01--27
COROLLA Supplement (RM1129E)
SYMPTOM SIMULATION
HINT:
The most difficult case in troubleshooting is when no problem symptoms occur. In such cases, a thorough
problem analysis must be carried out. A simulation of the same or similar conditions and environment in
which the problem occurred in the customer’s vehicle should be carried out. No matter how much skill or
experience a technician has, troubleshooting without confirming the problem symptoms will lead to important
repairs being overlooked and mistakes or delays.
For example:
With a problem that only occurs when the engine is cold or occurs as a result of vibration caused by the road
during driving, the problem can never be determined if the symptoms are being checked on a stationary ve-
hicle or a vehicle with a warmed--up engine.
Vibration, heat or water penetration (moisture) is difficult to reproduce. The symptom simulation tests below
are effective substitutes for the conditions and can be applied on a stationary vehicle.
Important points in the symptom simulation test:
In the symptom simulation test, the problem symptoms as well as the problem area or parts must be con-
firmed. First, narrow down the possible problem circuits according to the symptoms. Then, connect the tester
and carry out the symptom simulation test, judging whether the circuit being tested is defective or normal.
Also, confirm the problem symptoms at the same time. Refer to the problem symptoms table for each system
to narrow down the possible causes.
1.
VIBRATION METHOD: When vibration seems to be
the major cause.
(a)
PART AND SENSOR
(1)
Apply slight vibration with a finger to the part of the
sensor considered to be the cause of the problem
and check whether or not the malfunction occurs.
HINT:
Applying strong vibration to relays may open relays.
(b)
CONNECTORS
(1)
Slightly shake the connector vertically and horizon-
tally.
(c)
WIRE HARNESS
(1)
Slightly shake the wire harness vertically and hori-
zontally.
The connector joint and fulcrum of the vibration are
the major areas that should be checked thoroughly.
2.
HEAT METHOD: If the problem seems to occur when
the area in question is heated.
(a)
Heat the component that is the possible cause of the mal-
function with a hair dryer or similar device. Check if the
malfunction occurs.
NOTICE:
S
Do not heat to more than 60
_
C (140
_
F). Exceeding this
temperature may damage components.
S
Do not apply heat directly to the parts in the ECU.
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TOYOTA COROLLA REPAIR MANUAL SUPP 1129E
