Toyota Celica 2005 Repair Manual page 20

HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the CELICA. In general, the ECU controlled system
is considered to be a very intricate system requiring a high level of technical knowledge and expert skill to
troubleshoot. However, the fact is that if you proceed to inspect the circuits one by one, troubleshooting of
these systems is not complex. If you have adequate understanding of the system and a basic knowledge
of electricity, accurate diagnosis and necessary repair can be performed to locate and fix the problem. This
manual is designed through emphasis of the above standpoint to help service technicians perform accurate
and effective troubleshooting, and is compiled for the following major ECU controlled systems:
The troubleshooting procedure and how to make use of it are described on the following pages.
1. 1ZZ−FE Engine
2. 2ZZ−GE Engine
3. U240E Automatic Transaxle
4. U341E Automatic Transaxle
5. Anti−Lock Brake System with Electronic Brake Force Distribution (EBD)
6. Supplemental Restraint System
7. Cruise Control System (1ZZ−FE)
8. Cruise Control System (2ZZ−GE)
9. Body Control system
FOR USING OBD II SCAN TOOL OR TOYOTA HAND−HELD TESTER
Before using the scan tool or tester, the scan tool's instruction book or tester's operator manual should
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be read thoroughly.
If the scan tool or tester cannot communicate with ECU controlled systems when you have connected
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the cable of the scan tool or tester to DLC3, turned the ignition switch ON and operated the scan tool,
there is a problem on the vehicle side or tool side.
(1) If communication is normal when the tool is connected to another vehicle, inspect the diagnosis
data link line (Bus line) or ECU power circuit of the vehicle.
(2) If communication is still not possible when the tool is connected to another vehicle, the problem
is probably in the tool itself, so perform the Self Test procedures outline in the Tester Operator's
Manual.
2005 CELICA (RM1131U)
INTRODUCTION
System
− HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
19
Page
DI−1
DI−293
DI−666
DI−755
DI−834
DI−882
DI−1037
DI−1088
DI−1117
IN−19
IN05Y−45