01–24
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INTRODUCTION
HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
24
Author:
Date:
2002 CAMRY REPAIR MANUAL (RM881U)
SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE
HINT:
The diagnostic system in CAMRY has various functions. The first function is the Diagnostic Trouble
Code (DTC) Check in which a malfunction in the signal circuits to the ECU is stored in code form in
the ECU memory. Another function is the Input Signal Check which checks if the signals from various
switches are sent to the ECU correctly. By using these check functions, possible areas of the problem
can be narrowed down quickly and troubleshooting can be performed effectively. Diagnostic functions
are incorporated in the following systems in CAMRY.
System
Diagnostic Trouble
Code Check
Input Signal Check
(Sensor Check)
Diagnostic Test
Mode (Active Test)
SFI System
(with Check Mode)
ABS with EBD System
ABS with EBD & BA & TRAC & VSC System
Electronic Controlled Automatic Transmission [ECT]
(with Check Mode)
Air Conditioning System
Supplement Restraint System
Power Door Lock Control System
Wireless Door Lock Control System
Engine Immobiliser System
Body Multiplex Communication System
Cruise Control System
In the DTC check, it is very important to determine whether the problem indicated by the DTC is still
occurring or has occurred in the past but returned to normal at present. In addition, it must be checked
in the problem symptom check whether the malfunction indicated by the DTC is directly related to the
problem symptom or not. For this reason, the DTC should be checked before and after the symptom
confirmation to determine the current conditions. If this is not done, it may, depending on the case,
result in an unnecessary troubleshooting for normally operating systems, making it more difficult to de-
tect the problem area, or trying to repair irrelevant areas. Therefore always follow the procedure in the
correct order and perform the DTC check.
A flow chart showing how to proceed with the troubleshooting using the diagnostic trouble code (DTC)
check is shown below. This flow chart shows how to utilize the DTC check effectively Then, by carefully
checking the results, indicates how to proceed either to the DTC troubleshooting or to the troubleshoot-
ing of problem symptoms table.
1
DTC check
2
Making a note and clearing of the DTCs displayed
3
Symptom confirmation
Problem symptoms exist
No problem symptoms exist
a
Go to step 5