IN04S-45
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INTRODUCTION
HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
IN-21
21
Author:
Date:
2005 LEXUS IS300 (RM1140U)
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the LEXUS IS300. In general, ECU controlled sys-
tems are considered to be a very intricate, requiring a high level of technical knowledge to troubleshoot. How-
ever, following the problem checking procedures of the ECU controlled system’s circuits carefully is not com-
plex. If you have an adequate understanding of the system and a basic knowledge of electricity, accurate
diagnosis and necessary repair can be performed.
This manual emphasizes the above standpoint to help service technicians perform accurate and effective
troubleshooting. Detailed information on major ECU controlled systems in this vehicle are outlined below:
System
Page
1. Engine
2. Automatic Transmission
3. ABS with EBD & BA & TRAC System
4. ABS with EBD & BA & TRAC & VSC System
5. Supplemental Restraint System
6. Theft Deterrent System
7. Cruise Control System
8. Engine Immobiliser System
9. Combination Meter System
10.Body Control System
11.Multiplex Communication System
12.LEXUS Navigation System
13.Air Conditioning System
FOR USING OBDII SCAN TOOL OR HAND-HELD TESTER
Before using the scan tool or tester, the scan tool’s instruction book or tester’s operator manual should
be read thoroughly.
If the scan tool or tester cannot communicate with ECU controlled systems when you have connected
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 outlined in the Tester Operator’s
Manual.
