Lexus SC300 / Lexus SC400. Manual - part 5

INSPECTION AND ADJUSTMENT OF
JOINT ANGLE DURING REMOVAL
AND INSTALLATION OF
PROPELLER SHAFT

When performing operations which involve the removal and instal-
lation of the propeller shaft be sure to check the joint angle. Make
adjustment if necessary (See page 

PR–13

).

IN–14

–

INTRODUCTION

Inspection and Adjustment of Joint Angle During
Removal and Installation of Propeller Shaft

HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

A large number of ECU controlled systems are used in the LEXUS SC400. In general, the ECU controlled sys-
tem 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 de-
signed 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:

Repair Manual

System

Page

1. Engine

TR–1

V l 1

2. Automatic Transmission

AT–33

Vol. 1

3. Anti–Lock Brake

BR–43

4. Traction Control

BR–139

5. Steering Column Electronic Control

SR–22

6. SRS Airbag

AB–25

7. Power Seat Control

BE–265

V l 2

8. Door Lock Control

BE–347

Vol. 2

9. Theft Deterrent

BE–381

10. Wireless Door Lock Control

BE–425

11. Cruise Control

BE–459

12. Air Conditioner

AC–21

The troubleshooting procedure and how to make use of it are described on the following pages.

–

INTRODUCTION

How to Troubleshoot ECU Controlled Systems

IN–15

HOW TO PROCEED WITH TROUBLESHOOTING

Carry out troubleshooting in accordance with the procedure on the following page. Here, only the basic proce-
dure is shown. Details are provided in each section, showing the most effective methods for each circuit. Confirm
the troubleshooting procedures first for the relevant circuit before beginning troubleshooting of that circuit.

Ask the customer about the conditions and the
environment when the problem occurred.



 



Confirm the symptoms and the problem
conditions, and check the diagnostic codes.
(When the problem symptoms do not appear
during confirmation, use the symptom simu-
lation method described later on.)



 



 



Check the result obtained in Step 



, then

confirm the inspection procedure for the sys-
tem or the part which should be checked us-
ing the diagnostic code chart or the matrix
chart of problem symptoms.



Check and repair the affected system or part
in accordance with the instructions in Step 



.



After completing repairs, confirm that the
problem has been eliminated.
(If the problem is not reproduced, perform the
confirmation test under the same conditions
and in the same environment as when it oc-
curred for the first time.)

IN–16

–

INTRODUCTION

How to Troubleshoot ECU Controlled Systems

[1] CUSTOMER PROBLEM ANALYSIS
In troubleshooting, the problem symptoms must be confirmed accurately and all preconceptions must be
cleared away in order to give an accurate judgment. To ascertain just what the problem symptoms are, it is ex-
tremely important to ask the customer about the problem and the conditions at the time it occurred.
Important Points in the Problem Analysis
The following 5 items are important points in the problem analysis. Past problems which are thought to be unre-
lated and the repair history, etc. may also help in some cases, so as much information as possible should be
gathered and its relationship with the problem symptoms should be correctly ascertained for reference in trou-
bleshooting. A customer problem analysis table is provided in the troubleshooting section for each system for
your use.
Important Points in the Customer Problem Analysis

•

What                      Vehicle model, system name

•

When                     Date, time, occurrence frequency

•

Where                    Road conditions

•

Under what conditions?                   Running conditions, driving conditions, weather conditions

•

How did it happen?                          Problem symptoms

(Sample) Engine control system check sheet.

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INTRODUCTION

How to Troubleshoot ECU Controlled Systems

IN–17