Toyota SIENNA U Installation and operating manual

IN0I0-01
BO4111
Negative Cable
IN-10 -INTRODUCTION FOR ALL OF VEHICLES
10Author: Date:
2001 SIENNA (RM787U)
FOR ALL OF VEHICLES
PRECAUTION
1. FOR VEHICLES EQUIPPED WITH SRS AIRBAG AND
SEAT BELT PRETENSIONER
(a) The SIENNA is equipped with an SRS (Supplemental Re-
straint System), such as the driver airbag, front passen-
ger airbag assembly, side airbag assembly and seat belt
pretensioner.
Failure to carry out service operations in the correct se-
quence could cause the supplemental restraint system to
unexpectedly deploy during servicing, possibly leading to
a serious accident.
Further, if a mistake is made in servicing the supplemental
restraint system, it is possible the SRS may fail to operate
when required. Before servicing (including removal or
installation of parts, inspection or replacement), be sure
to read the following items carefully, then follow the cor-
rect procedure described in this manual.
(b) GENERAL NOTICE
(1) Malfunction symptoms of the supplemental re-
straint system are difficult to confirm, so the diag-
nostic trouble codes become the most important
source of information when troubleshooting. When
troubleshooting the supplemental restraint system,
always inspect the diagnostic trouble codes before
disconnecting the battery (See page DI-358 ).
(2) Work must be started after 90 seconds from the
time the ignition switch is turned to the ”LOCK” posi-
tion and the negative (-) terminal cable is discon-
nected from the battery.
(The supplemental restraint system is equipped
with a back-up power source so that if work is
started within 90 seconds of disconnecting the neg-
ative (-) terminal cable from the battery, the SRS
may deploy.)
When the negative (-) terminal cable is discon-
nected from the battery, memory of the clock and
audio systems will be cancelled. So before starting
work, make a record of the contents memorized by
the each memory system. Then when work is fin-
ished, reset the clock and audio systems as before.
To avoid erasing the memory of each memory sys-
tem, never use a back-up power supply from anoth-
er battery.

R11910
Red Mark
-INTRODUCTION FOR ALL OF VEHICLES IN-11
11Author: Date:
2001 SIENNA (RM787U)
(3) Even in cases of a minor collision where the SRS
does not deploy, the steering wheel pad, front pas-
senger airbag assembly and seat belt pretensioner
should be inspected (See page RS-14 , RS-28 ,
and BO-155 ).
(4) Never use SRS parts from another vehicle. When
replacing parts, replace them with new parts.
(5) Before repairs, remove the airbag sensor if shocks
are likely to be applied to the sensor during repairs.
(6) Never disassemble and repair the airbag sensor as-
sembly, steering wheel pad, front passenger airbag
assembly or seat belt pretensioner.
(7) If the airbag sensor assembly, steering wheel pad,
front passenger airbag assembly or seat belt pre-
tensioner have been dropped, or if there are cracks,
dents or other defects in the case, bracket or con-
nector, replace them with new ones.
(8) Do not directly expose the airbag sensor assembly,
steering wheel pad, front passenger airbag assem-
bly or seat belt pretensioner to hot air or flames.
(9) Use a volt/ohmmeter with high impedance (10 kΩ/V
minimum) for troubleshooting of the electrical cir-
cuit.
(10) Information labels are attached to the periphery of
the SRS components. Follow the instructions on the
notices.
(11) After work on the supplemental restraint system is
completed, check the SRS warning light (See page
DI-358 ).
(c) SPIRAL CABLE (in Combination Switch)
The steering wheel must be fitted correctly to the steering
column with the spiral cable at the neutral position, other-
wise cable disconnection and other troubles may result.
Refer to SR-20 of this manual concerning correct steer-
ing wheel installation.

B09710
Example: Correct Wrong
Z13950
Example:
IN-12 -INTRODUCTION FOR ALL OF VEHICLES
12Author: Date:
2001 SIENNA (RM787U)
(d) STEERING WHEEL PAD (with Airbag)
(1) When removing the steering wheel pad or handling
a new steering wheel pad, it should be placed with
the pad top surface facing up.
In this case, care should be taken to place it so the
connector will not be damaged. In addition do not
store a steering wheel pad on top of another one.
Storing the pad with its metallic surface up may lead
to a serious accident if the airbag inflates for some
reason.
(2) Never measure the resistance of the airbag squib.
(This may cause the airbag to deploy, which is very
dangerous.)
(3) Grease should not be attached to the steering
wheel pad and the pad should not be cleaned with
detergents of any kind.
(4) Store the steering wheel pad where the ambient
temperature remains below 93°C (200°F), without
high humidity and away from electrical noise.
(5) When using electric welding, first disconnect the air-
bag connector (yellow color and 2 pins) under the
steering column near the combination switch con-
nector before starting work.
(6) When disposing of a vehicle or the steering wheel
pad alone, the airbag should be deployed using an
SST before disposal (See page RS-16 ).
Carry out the operation in a safe place away from
electrical noise.

B02919
Example:
Correct Wrong
Z13951
Example:
-INTRODUCTION FOR ALL OF VEHICLES IN-13
13Author: Date:
2001 SIENNA (RM787U)
(e) FRONT PASSENGER AIRBAG ASSEMBLY
(1) Always store a removed or new front passenger air-
bag assembly with the airbag deployment direction
facing up.
Storing the airbag assembly with the airbag deploy-
ment direction facing down could cause a serious
accident if the airbag inflates.
(2) Never measure the resistance of the airbag squib.
(This may cause the airbag to deploy, which is very
dangerous.)
(3) Grease should not be applied to the front passen-
ger airbag assembly and the airbag door should not
be cleaned with detergents of any kind.
(4) Store the airbag assembly where the ambient tem-
perature remains below 93°C (200°F), without high
humidity and away from electrical noise.
(5) When using electric welding, first disconnect the air-
bag connector (yellow color and 2 pins) installed on
the assembly before starting work.
(6) When disposing of a vehicle or the airbag assembly
alone, the airbag should be deployed using an SST
before disposal (See page RS-30 ).
Perform the operation in a safe place away from
electrical noise.

B02922
Example: Correct Wrong
N21642
Example:
IN-14 -INTRODUCTION FOR ALL OF VEHICLES
14Author: Date:
2001 SIENNA (RM787U)
(f) SIDE AIRBAG ASSEMBLY
(1) Always store a removed or new side airbag assem-
bly with the airbag deployment direction facing up.
Storing the airbag assembly with the airbag deploy-
ment direction facing down could cause a serious
accident if the airbag deploys.
(2) Never measure the resistance of the airbag squib.
(This may cause the airbag to deploy, which is very
dangerous.)
(3) Grease should not be applied to the side airbag as-
sembly and the surface should not be cleaned with
detergents of any kind.
(4) Store the airbag assembly where the ambient tem-
perature remains below 93°C (200°F), without high
humidity and away from electrical noise.
(5) When using electric welding, first disconnect the air-
bag connector (yellow color and 2 pins) under the
seat before starting work.
(6) When disposing of a vehicle or the side airbag as-
sembly alone, the airbag should be deployed using
an SST before disposal (See page RS-42 ).
Perform the operation in a safe place away from
electrical noise.

B02121
Example:
-INTRODUCTION FOR ALL OF VEHICLES IN-15
15Author: Date:
2001 SIENNA (RM787U)
(g) SEAT BELT PRETENSIONER
(1) Never measure the resistance of the seat belt pre-
tensioner. (This may cause the seat belt pretension-
er activation which is very dangerous.)
(2) Never disassemble the seat belt pretensioner.
(3) Never install the seat belt pretensioner in another
vehicle.
(4) Store the seat belt pretensioner where the ambient
temperature remains below 80°C (176°F) and
away from electrical noise without high humidity.
(5) When using electric welding, first disconnect the
connector (yellow color and 2 pins) before starting
work.
(6) When disposing of a vehicle or the seat belt preten-
sioner alone, the seat belt pretensioner should be
activated before disposal (See page BO-156 ). Per-
form the operation in a safe place away from electri-
cal noise.
(7) The seat belt pretensioner is hot after activation, so
let it cool down sufficiently before the disposal.
However never apply water to the seat belt preten-
sioner.

IN-16 -INTRODUCTION FOR ALL OF VEHICLES
16Author: Date:
2001 SIENNA (RM787U)
(h) AIRBAG SENSOR ASSEMBLY
(1) Never reuse the airbag sensor assembly involved
in a collision when the SRS has deployed.
(2) The connectors to the airbag sensor assembly
should be connected or disconnected with the sen-
sor mounted on the floor. If the connectors are con-
nected or disconnected while the airbag sensor as-
sembly is not mounted to the floor, it could cause
undesired ignition of the supplemental restraint sys-
tem.
(3) Work must be started after 90 seconds from the
time the ignition switch is turned to the ”LOCK” posi-
tion and the negative (-) terminal cable is discon-
nected from the battery, even if only loosing the set
bolts of the airbag sensor assembly.
(i) WIRE HARNESS AND CONNECTOR
The SRS wire harness is integrated with the instrument
panel wire harness assembly. All the connectors in the
system are a standard yellow color. If the SRS wire har-
ness becomes disconnected or the connector becomes
broken due to an accident, etc., repair or replace it as
shown on page RS-66 .

-INTRODUCTION FOR ALL OF VEHICLES IN-17
17Author: Date:
2001 SIENNA (RM787U)
2. 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.
3. 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) Do not wind the antenna feeder together with the other wiring as much as possible, 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.

IN-18 -INTRODUCTION FOR ALL OF VEHICLES
18Author: Date:
2001 SIENNA (RM787U)
4. FOR USING OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER
CAUTION:
Observe the following items for safety reasons:
Before using the OBD II scan tool or TOYOTA hand-held tester, the OBD II scan tool’s instruc-
tion book or TOYOTA hand-held tester’s operator manual should be read thoroughly.
Be sure to route all cables securely when driving with the OBD II scan tool or TOYOTA hand-
held tester connected to the vehicle. (i.e. Keep cables away from feet, pedals, steering wheel
and shift lever.)
Two persons are required when test driving with the OBD II scan tool or TOYOTA hand-held
tester, one person to drive the vehicle and the other person to operate the OBD II scan tool or
TOYOTA hand-held tester.
5. FOR VEHICLES EQUIPPED WITH POWER SLIDE DOOR CONTROL SYSTEM
When the battery is disconnected or the power to the power slide door motor is cut, the power slide door
control system does not operate. It is necessary to initialize the system in the following procedures. Other-
wise slide door cannot be operated normally.
(1) Disconnect the battery negative (-) terminal for more than 1 min., and install it.
(2) Close the RH slide door manually.
(3) Push the power slide door MAIN switch ON and wait for 5 secs.
(4) Fully open the slide door by the power slide door control switch and wait for 3 secs.
(5) Fully close the slide door by the power slide door control switch and wait for 3 secs.
(6) Repeat the step (4) and (5).

B12976
w/o Tachometer:
w/ Tachometer:
B12977
-INTRODUCTION FOR ALL OF VEHICLES IN-19
19Author: Date:
2001 SIENNA (RM787U)
6. FOR VEHICLES EQUIPPED WITH TRACTION CON-
TROL (TRAC) & VEHICLE SKID CONTROL (VSC) SYS-
TEM
NOTICE:
When replacing the steering angle sensor or ECU, or
when adjusting the front wheel alignment or steering
wheel center point in accordance with the removing
and installing or replacing the suspension, axle, or
steering parts, make sure to perform the steering
angle sensor zero point calibration (See page
DI-259 ).
Do not remove or install the VSC related parts unless
necessary. Otherwise, there is a possibility that the
setting of the VSC to be affected.
When working on the VSC related operation, make
sure to check that the preparations before and after
work are completed according to the following
instruction.
When using a 2- wheel drum tester such as a
speedometer tester or chassis dynamometer, etc., or
jacking up the front wheels and driving the wheels, al-
ways push in the TRAC & VSC cut (”TRAC OFF”)
switch and turn the TRAC & VSC system OFF.
(a) Press the TRAC OFF switch.
(b) Check that the TRAC OFF indicator light comes ON.
HINT:
The TRAC OFF indicator light should be always OFF when the
engine is restarted.
(c) Begin measurements.
(d) Press the TRAC OFF switch again to change the TRAC
& VSC system to operational condition and check that the
TRAC OFF indicator light goes off.
HINT:
The SLIP indicator light blinks when the TRAC system is
operational.
The SLIP indicator light blinks and the VSC buzzer
sounds when the VSC system is operational.

IN05Y-27
IN-20 -INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS
20Author: Date:
2001 SIENNA (RM787U)
HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS
GENERAL INFORMATION
A large number of ECU controlled systems are used in the SIENNA. 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.
System Page
1. Engine DI-1
2. AutomaticTransaxle DI-155
3. Tire Pressure Warning System DI-207
4. Anti-Lock Brake System DI-218
5. ABS with EBD & BA & TRAC & VSC System DI-257
6. Supplemental Restraint System DI-356
7. Power Slide Door Control System DI-501
8. Theft Deterrent System DI-516
9. Cruise Control System DI-561
10.Engine Immobiliser System DI-606
11.Body Control System DI-628
12.Air Conditioning System DI-687
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
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 outline in the Tester Operator’s
Manual.

IN05W-29
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
-INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS IN-21
21Author: Date:
2001 SIENNA (RM787U)
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.

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.
ENGINE CONTROL SYSTEM Check Sheet
Customer’s Name
Driver’s Name
Data Vehicle
Brought in
License No.
Model and Model
Year
Frame No.
Engine Model
Odometer Reading km
miles
Problem Symptoms
Engine does
not Start
Difficult to
Start
Poor Idling
Poor
Drive ability
Engine Stall
Others
Engine does not crank No initial combustion No complete combustion
Engine cranks slowly
Other
Incorrect first idle Idling rpm is abnormal High ( rpm) Low ( rpm)
Rough idling Other
Hesitation Back fire Muffler explosion (after-fire) Surging
Knocking Other
Soon after starting After accelerator pedal depressed
After accelerator pedal released During A/C operation
Shifting from N to D Other
Data Problem
Constant Sometimes ( times per day/month)
Inspector’s
Name
CUSTOMER PROBLEM ANALYSIS CHECK
IN-22 -INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS
22Author: Date:
2001 SIENNA (RM787U)
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
extremely important to ask the customer about the problem and the conditions at the time it occurred.
Important Point in the Problem Analysis:
The following 5 items are important points in the problem analysis. Past problems which are thought to be
unrelated 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 troubleshooting. A customer problem analysis table is provided in Diagnostics section for each system
for your use.

DIAGNOSTIC TROUBLE CODE CHECK PROCEDURE
Diagnostic Trouble
Code Check (Make a
note of and then clear)
Confirmation
of Symptoms Diagnostic Trouble Code Check Problem Condition
Diagnostic Trouble
Code Display Problem symptoms
exist Same diagnostic
trouble code is
displayed
Problem is still occurring in the diagnostic
circuit
Normal code is
displayed The problem is still occurring in a place
other than in the diagnostic circuit
(The diagnostic trouble code displayed
first is either for a past problem or it is a
secondary problem)
No problem
symptoms exist The problem occurred in the diagnostic circuit in the past
Normal Code Display Problem symptoms
exist Normal code is displayed The problem is still occurring in a place
other than in the diagnostic circuit
No problem
symptoms exist Normal code is displayed The problem occurred in a place other than in the diagnostic circuit in the past
-INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS IN-23
23Author: Date:
2001 SIENNA (RM787U)
2. SYMPTOM CONFIRMATION AND DIAGNOSTIC TROUBLE CODE CHECK
The diagnostic system in the SIENNA fulfills various functions. The first function is the Diagnostic Trouble
Code Check in which a malfunction in the signal circuits to the ECU is stored in code in the ECU memory
at the time of occurrence, to be output by the technician during troubleshooting. Another function is the Input
Signal Check which checks if the signals from various switches are sent to the ECU correctly.
By using these check functions, the problem areas can be narrowed down quickly and troubleshooting can
be performed effectively. Diagnostic functions are incorporated in the following systems in the SIENNA.
System DiagnosticTrouble
Code Check Input Signal Check (Sensor Check) Diagnostic Test Mode (Active Test)
Engine
Automatic Transaxle
Anti-Lock Brake System
ABS with EBD & BA & TRAC & VSC System
Supplemental Restraint System
Cruise Control System
Power Slide Door Control System
Air Conditioning System
(with Test Mode)
(with Test Mode)












In diagnostic trouble code check, it is very important to determine whether the problem indicated by the diag-
nostic trouble code is still occurring or occurred in the past but returned to normal at present. In addition,
it must be checked in the problem symptom check whether the malfunction indicated by the diagnostic
trouble code is directly related to the problem symptom or not. For this reason, the diagnostic trouble codes
should be checked before and after the symptom confirmation to determine the current conditions, as shown
in the table below. If this is not done, it may, depending on the case, result in unnecessary troubleshooting
for normally operating systems, thus making it more difficult to locate the problem, or in repairs not pertinent
to the problem. Therefore, always follow the procedure in correct order and perform the diagnostic trouble
code check.

Diagnostic trouble code check
Making a note of and clearing of the diagnostic trouble codes displayed
Symptom confirmation No problem symptoms
exist
Problem symptoms
exist
Simulation test using the symptom
simulation methods
Normal code displayed
Problem symptoms exist Normal code displayed
No problem symptoms exist
Diagnostic trouble code check
Troubleshooting of problem indicated
by diagnostic trouble code
Diagnostic trouble code displayed
Problem symptoms exist
System Normal
Troubleshooting of each
problem symptom If a diagnostic trouble code was
displayed in the initial diagnostic
trouble code check, it indicates
that the trouble may have occurred
in a wire harness or connector in
that circuit in the past. Therefore,
check the wire harness and con-
nectors (See page IN-31 ).
IN-24 -INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS
24Author: Date:
2001 SIENNA (RM787U)
Taking into account the above points, a flow chart showing how to proceed with troubleshooting using the
diagnostic trouble code check is shown below. This flow chart shows how to utilize the diagnostic trouble
code check effectively, then by carefully checking the results, indicates how to proceed either to diagnostic
trouble code troubleshooting or to troubleshooting of problem symptoms table.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR
1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check that the mal-
function occurs.
Shake Slightly
Swing Slightly
Vibrate Slightly
HINT:
Applying strong vibration to relays may result in open relays.
-INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS IN-25
25Author: Date:
2001 SIENNA (RM787U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer’s vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot condition or the
vehicle at a standstill. Since vibration, heat or water penetration (moisture) is likely cause for problem which
is difficult to reproduce, the symptom simulation tests introduced here are effective measures in that the ex-
ternal causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the problem symptoms table for each system to narrow down the possible
causes of the symptom.

B02389
B02390
HEAT METHOD: When the problem seems to occur when the suspect area is heated.2
NOTICE:
3 WATER SPRINKLING METHOD:
(1)
(2)
4 OTHER: When a malfunction seems to occur when electrical load is excessive.
When the malfunction seems to occur on a rainy day or in a
high-humidity condition.
Heat the component that is the likely cause of the malfunction
with a hair dryer or similar object. Check to see if the malfunction
occurs.
Sprinkle water onto the vehicle and check to see if the malfunc-
tion occurs.
Turn on all electrical loads including the heater blower, head
lights, rear window defogger, etc. and check to see if the mal-
function occurs.
ON
HINT:
If a vehicle is subject to water leakage, the leaked water may
contaminate the ECU. When testing a vehicle with a water leak-
age problem, special caution must be taken.
Malfunc-
tion
Do not heat to more than 60 °C (140 °F). (Temperature
is limited not to damage the components.)
Do not apply heat directly to parts in the ECU.
(1)
(2)
Never sprinkle water directly into the engine compart-
ment, but indirectly change the temperature and hu-
midity by applying water spray onto the radiator front
surface.
Never apply water directly onto the electronic compo-
nents.
NOTICE:
IN-26 -INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS
26Author: Date:
2001 SIENNA (RM787U)

DTC No.
Indicates the diagnostic trouble code.
Page or Instructions
Indicates the page where the inspection procedure
for each circuit is to be found, or gives instructions
for checking and repairs.
Detection Item
Indicates the system of the problem or
contents of the problem.
Trouble Area
Indicates the suspect area of the
problem.
Mass Air Flow Circuit Malfunction
Detection Item
Open or short in mass air flow meter circuit
Mass air flow meter
ECM
DTC No.
(See page) Trouble Area MIL* Memory
P0100
(DI-24)
P0101
(DI-28)
P0115
(DI-33)
Open or short in intake air temp. sensor
circuit
Intake air temp. sensor
ECM
Intake Air Temp. Circuit
Malfunction
P0110
(DI-29)
Open or short in engine coolant temp. sensor circuit
Engine coolant temp. sensor
ECM
Throttle/ Pedal Position Sensor/Switch
”A” Circuit Malfunction
Engine Coolant Temp.
Circuit Malfunction
Open or short in throttle position sensor circuit
Throttle position sensor
ECM
DTC CHART (SAE Controlled)
HINT:
Parameters listed in the chart may not be exactly the same as your reading due to the type of instrument or other
factors.
If a malfunction code is displayed during the DTC check mode, check the circuit for that code listed in the table
below. For details of each code, turn to the page referred to under the ”See page” for the respective ”DTC No.”
in the DTC chart.
Mass Air Flow Circuit
Range/ Performance Problem Mass air flow meter
Throttle position sensor
Throttle/Pedal Position Sensor/ Switch
”A” Circuit Range / Performance Prob-
lem
P0116
(DI-37) Engine Coolant Temp. Circuit Range/ Performance Problem
Engine coolant temp. sensor
Cooling system
-INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS IN-27
27Author: Date:
2001 SIENNA (RM787U)
4. DIAGNOSTIC TROUBLE CODE CHART
The inspection procedure is shown in the table below. This table permits efficient and accurate troubleshoot-
ing using the diagnostic trouble codes displayed in the diagnostic trouble code check. Proceed with trouble-
shooting in accordance with the inspection procedure given in the diagnostic chart corresponding to the
diagnostic trouble codes displayed. The engine diagnostic trouble code chart is shown below as an example.

IN-28 -INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS
28Author: Date:
2001 SIENNA (RM787U)
5. PROBLEM SYMPTOMS TABLE
The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to
troubleshoot the problem when a ”Normal” code is displayed in the diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the problem symptom is present,
it is considered that the problem is occurring outside the detection range of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.
Symptom Suspect Area See page
Engine does not crank (Does not start)
No initial combustion (Does not start)
No complete combustion (Does not start)
1. Starter and starter relay
1. ECM power source circuit
2. Fuel pump control circuit
3. Engine control module (ECM)
1. Starter signal circuit
2. Fuel pump control circuit
1. Fuel pump control circuit
DI-147
DI-151
IN-29
PROBLEM SYMPTOMS TABLE
1. Compression
2. Fuel pump control circuit
1. A/C signal circuit
2. Fuel pump control circuit
1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit
1. Starter signal circuit
2. Fuel pump control circuit
1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
idling)
High engine idle speed (Poor idling)
Hot engine
Cold engine (Difficult to start)
Engine cranks normally (Difficult to start)
AC-88
DI-144
DI-151
EM-3
DI-151
Problem Symptom
Page
Indicates the page where the flow chart for each circuit
is located.
Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.
Circuit or Part Name
Indicates the circuit or part which needs to be checked.
ST-2
ST-17
DI-144
DI-151
DI-144
DI-151

V08423
Knock Sensor 1 GR
ECM
KNK
E1
12
E6
WIRING DIAGRAM Wiring Diagram
This shows a wiring diagram of the circuit.
Use this diagram together with ELECTRICAL
WIRING DIAGRAM to thoroughly understand the
circuit.
Wire colors are indicated by an alphabetical code.
B = Black, L = Blue, R = Red, BR = Brown,
LG = Light Green, V = Violet, G = Green,
O = Orange, W = White, GR = Gray, P = Pink,
Y = Yellow, SB = Sky Blue
The first letter indicates the basic wire color and
the second letter indicates the color of the stripe.
DTC P0325 Knock Sensor 1 Circuit Malfunction
CIRCUIT DESCRIPTION
Knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which
generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine
knocking occurs, ignition timing is retarded to suppress it.
DTC No. DTC Detecting Condition Trouble Area
P0325 No knock sensor 1 signal to ECM with engine speed,
1,200 rpm or more.
Open or short in knock sensor1 circuit
Knock sensor 1 (looseness)
ECM
If the ECM detects the above diagnosis conditions, it operates the fall safe function in which the corrective retard angle
value is set to the maximum value.
Diagnostic Trouble Code No. and Detection Item
Circuit Description
The major role and operation, etc. of the circuit
and its component parts are explained.
Indicates the diagnostic trouble code, diagnostic
trouble code set parameter and suspect area of
the problem.

-INTRODUCTION HOW TO TROUBLESHOOTECU CONTROLLED
SYSTEMS IN-29
29Author: Date:
2001 SIENNA (RM787U)
6. CIRCUIT INSPECTION
How to read and use each page is shown below.