Lexus RX300 (MCU15). Manual - part 77

B13136

Conditions

Towing Method

1. Flat Bed Truck

Parking Brake

Any Position

2. Wheel Lift Type Truck

Applied

Transaxle Shift
Lever Position

Applied

From Rear

Any Position

From Front

B13137

NO

D

NO

If this towing method is used, either from the front or rear, there is
a danger of the drive train heating up and causing breakdown, or of
the front wheels flying off the dolly.

D Never tow the vehicle using a method where the lifted–up wheel can-

not rotate.

D

Do not use the sling type towing method, either from the front or
rear, as this method causes damage to the body.

–

INTRODUCTION

FOR ALL OF VEHICLES

IN–19

LEXUS RX300   (RM785E)

3.

WHEN TOWING FULL–TIME 4WD VEHICLES

S

Use one of the methods shown below to tow the vehicle.

S

If the vehicle has trouble in the chassis and drive train, use method 1 (flat bed truck).

NOTICE:
Do not use any towing method other than those shown above.
For example, the towing methods shown below are dangerous or damage the vehicle, so do not use them.

IN–20

–

INTRODUCTION

FOR ALL OF VEHICLES

LEXUS RX300   (RM785E)

4.

FOR VEHICLES EQUIPPED WITH A CATALYTIC CONVERTER

CAUTION:
If large amount of unburned gasoline flows into the converter, it may overheat and create a fire haz-
ard. To prevent this, observe the following precautions and explain them to your customer.
(a)

Use only unleaded gasoline.

(b)

Avoid prolonged idling.
Avoid running the engine at idle speed for more than 20 minutes.

(c)

Avoid spark jump test.
(1)

Perform spark jump test only when absolutely necessary. Perform this test as rapidly as possible.

(2)

While testing, never race the engine.

(d)

Avoid prolonged engine compression measurement.
Engine compression tests must be done as rapidly as possible.

(e)

Do not run engine when fuel tank is nearly empty.
This may cause the engine to misfire and create an extra load on the converter.

(f)

Avoid coasting with ignition turned off.

(g)

Do not dispose of used catalyst along with parts contaminated with gasoline or oil.

5.

IF VEHICLE IS EQUIPPED WITH MOBILE COMMUNICATION SYSTEM

For vehicles with mobile communication systems such as two–way radios and cellular telephones, observe
the following precautions.

(1)

Install the antenna as far as possible away from the ECU and sensors of the vehicle’s electronic
system.

(2)

Install the antenna feeder at least 20 cm (7.87 in.) away from the ECU and sensors of the ve-
hicle’s electronic systems. For details about ECU and sensors locations, refer to the section on
the applicable component.

(3)

Avoid winding the antenna feeder together with other wiring as much as possible, and also avoid
running the antenna feeder parallel with other wire harnesses.

(4)

Check that the antenna and feeder are correctly adjusted.

(5)

Do not install powerful mobile communications system.

6.

FOR USING HAND–HELD TESTER

CAUTION:
Observe the following items for safety reasons:

S

Before using the hand–held tester, the hand–held tester’s operator manual should be read thor-
oughly.

S

Be sure to route all cables securely when driving with the hand–held tester connected to the
vehicle. (i.e. Keep cables away from feet, pedals, steering wheel and shift lever.)

S

Two persons are required when test driving with the hand–held tester, one person to drive the
vehicle and the other person to operate the hand–held tester.

IN05Y–24

–

INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED 
SYSTEMS

IN–21

LEXUS RX300   (RM785E)

HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS

GENERAL INFORMATION

A large number of ECU controlled systems are used in the LEXUS RX300. 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.

System

Page

1. Engine

DI–1

2. Automatic Transaxle

DI–142

3. ABS & BA & TRC & VSC System

DI–203

4. Supplemental Restraint System

DI–303

5. Theft Deterrent System

DI–443

6. Cruise Control System

DI–472

7. Engine Immobiliser System

DI–520

8. Combination Meter System

DI–537

9. Sliding Roof System

DI–553

10. Body Control System

DI–564

11. Driver Door Control System

DI–598

12. Passenger Door Control System

DI–620

13. Rear Left Door Control System

DI–642

14. Rear Right Door Control System

DI–659

15. Multiplex Communication System

DI–676

16. LEXUS Navigation System

DI–726

17. Air Conditioning System

DI–803

FOR USING HAND–HELD TESTER

S

Before using the tester, the tester’s operator manual should be read thoroughly.

S

If the tester cannot communicate with ECU controlled systems when you have connected the cable
of the 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 (Busęline) 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.

IN05W–26

Vehicle Brought to Workshop

Customer Problem
Analysis

Symptom Confirmation
and Diagnostic Trouble
Code Check

Symptom Simulation

Diagnostic Trouble 
Code Chart

Problem Symptoms Table

Circuit Inspection or Parts
Inspection

Repair

Confirmation Test

End

1

2

4

3

5

6

7

8

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

1

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

2, 3

Check the results obtained in Step 2, then confirm 
the inspection procedure for the system or the part
which should be checked using the diagnostic
trouble code chart or the problem symptoms table.

4, 5, 6

Check and repair the affected system or part in 
accordance with the instructions in Step 6.

7

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 occurred for
the first time.)

8

IN–22

–

INTRODUCTION

HOW TO TROUBLESHOOT ECU CONTROLLED 
SYSTEMS

LEXUS RX300   (RM785E)

HOW TO PROCEED WITH TROUBLESHOOTING

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