Toyota 1996 LAND CRUISER User Manual page 18

HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the LAND CRUISER. 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, troubleshoot-
ing of these systems is not complex. If you have adequate understanding of the system and a basic knowl-
edge 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 ac-
curate 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. Engine
2. Automatic Transmission
3. Anti−Lock Brake System
4. Supplemental Restraint System
5. Cruise 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.
1996 LAND CRUISER (RM451U)
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INTRODUCTION
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− HOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
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Date : 17