ECU TOYOTA HIGHLANDER 2023 Repair Manual

3786-2. Maintenance
General maintenance
Listed below are the general
maintenance items that
should be performed at the
intervals specified in the
“Owner’s Warranty Informa-
tion Booklet” or “Owner’s
Manual Supplement/Sched-
uled Maintenance Guide”. It
is recommended that any
problem you notice should
be brought to the attention
of your Toyota dealer or
qualified service shop for
advice.
WARNING
■If the engine is running
Turn the engine off and ensure
that there is adequate ventilation
before performing maintenance
checks.
Engine compartment
ItemsCheck points
BatteryCheck the connec-
tions. ( P.391)
Brake fluid
Is the brake fluid at
the correct level?
( P.390)
Engine coolant
Is the engine cool-
ant at the correct
level? ( P.389)
Engine oil
Is the engine oil at
the correct level?
( P.386)
Exhaust sys-
temThere should not
be any fumes or
strange sounds.
Radiator/con-
denser
The radiator and
condenser should
be free from for-
eign objects.
( P.390)
Washer fluid
Is there sufficient
washer fluid?
( P.392)
Vehicle interior
ItemsCheck points
Accelerator
pedal
• The accelerator
pedal should
move smoothly
(without uneven
pedal effort or
catching).
Automatic
transmission
“Park” mecha-
nism
• When parked on a slope and the
shift lever is in P,
is the vehicle
securely
stopped?
ItemsCheck points

3796-2. Maintenance
6
Maintenance and care
Brake pedal
• Does the brake pedal move
smoothly?
• Does the brake pedal have
appropriate
clearance from
the floor?
( P.479)
• Does the brake pedal have the
correct amount
of free play?
( P.479)
Brakes
• The vehicle
should not pull to
one side when
the brakes are
applied.
• The brakes should work
effectively.
• The brake pedal should not feel
spongy.
• The brake pedal should not get
too close to the
floor when the
brakes are
applied.
Head
restraints
• Do the head restraints move
smoothly and
lock securely?
Horn• Works properly?
Indica-
tors/buzzers
• Do the indica-tors and buzzers
function prop-
erly?
ItemsCheck points
Lights
• Do all the lights come on?
• Are the head- lights aimed cor-
rectly? (P.414)
Parking brake
• Does the park-ing brake switch
operate nor-
mally?
• When parked on a slope and the
parking brake is
on, is the vehicle
securely
stopped?
Seat belts
• Do the seat belts operate
smoothly?
• The seat belts should not be
damaged.
Seats
• Do the seat con-trols operate
properly?
Steering wheel
• Does the steer-ing wheel rotate
smoothly?
• Does the steer- ing wheel have
the correct
amount of free
play?
• There should not be any strange
sounds coming
from the steer-
ing wheel.
ItemsCheck points

3846-3. Do-it-yourself maintenance
1Pull the hood lock release
lever.
The hood will pop up slightly.
2Pull up the auxiliary catch
lever and lift the hood.
3 Hold the hood open by insert-
ing the support rod into the
slot.
Hood
Opening the hood
WARNING
■Pre-driving check
Check that the hood is fully closed
and locked.
If the hood is not locked properly,
it may open while the vehicle is in
motion and cause an accident,
which may result i n death or seri-
ous injury.
■To prevent a injuries
The support rod may be hot after
driving the vehicle. Touching the
hot support rod may lead to burns
or other serious injuries.
■After installing the support
rod into the slot
Make sure the rod supports the
hood securely preventing it from
falling down onto your head or
body.
NOTICE
■When the hood is open
Even if the engine switch is turned
off, the cooling fan may continue
to operate for a short time. When
the cooling fan is rotating, do not
touch or approac h the inside of
the engine compartment.
■When closing the hood
Be sure to return the support rod
to its clip before closing the hood.
Closing the hood with the support
rod not clipped could cause the
hood to bend.

4176-3. Do-it-yourself maintenance
6
Maintenance and care
securely installed and turn the lights
and turn signal lights on to visually
check that there is no light leaking
from between the bulb base and
light unit.
■Front side marker lights
1 Turn the bulb base counter-
clockwise and remove it.
2 Remove the light bulb.
3 Install a new light bulb, and
then install the bulb base to
the light unit by inserting it
and turning the bulb base
clockwise.
After installing th e bulb base, wig- gle it lightly to make sure it is
securely installed a
nd turn the lights
on to visually check that there is no
light leaking from between the bulb
base and light unit.
■Rear turn signal lights
1 Open the back door and
using a flathead screwdriver,
remove the cover.
To prevent damage to the vehicle,
wrap the tip of th e flathead screw-
driver with tape, etc.
2 Remove the securing 2
screws and light unit.
Remove the light u nit by pulling it
straight back from the rear of the

4186-3. Do-it-yourself maintenance
vehicle.
3Disconnect the wire harness.
4 Turn the bulb base counter-
clockwise and remove it.
5 Remove the light bulb. 6
Install a new light bulb, and
then install the bulb base to
the light unit by inserting it
and turning it clockwise.
After installing the bulb base, wig-
gle it lightly to make sure it is
securely installed and turn on the
turn signal lights to visually check
that there is no light leaking from
between the bulb base and light
unit.
7Install the light unit.
Align the 2 guides and push the
light unit toward the front of the
vehicle to install it.

4196-3. Do-it-yourself maintenance
6
Maintenance and care
8Install the 2 screws.
9 Install the cover.
■Back-up lights
1 Open the back door and
remove the cover.
Using a flathead screwdriver,
remove the cover.
To prevent damage to the vehicle,
wrap the tip of the flathead screw-
driver with tape, etc.
2Turn the bulb base counter-
clockwise and remove it.
3 Remove the light bulb.
4 Install a new light bulb, and
then install the bulb base to
the light unit by inserting it
and turning it clockwise.
After installing the bulb base, wig-
gle it lightly to make sure it is
securely installed and turn on the
back-up lights to visually check that
there is no light leaking from
between the bulb base and light
unit.
5Install the cover.

4226-3. Do-it-yourself maintenance
WARNING
●Do not touch the glass portion
of the light bulb with bare
hands. When it is unavoidable
to hold the glass portion, use
and hold with a clean dry cloth
to avoid getting moisture and
oils on the bulb. Also, if the bulb
is scratched or dropped, it may
blow out or crack.
●Fully install light bulbs and any
parts used to secure them. Fail-
ure to do so may result in heat
damage, fire, or water entering
the light unit. This may damage
the lights or cause condensa-
tion to build up on the lens.
●Do not attempt t o repair or dis-
assemble light bulbs, connec-
tors, electric circuits or
component parts.
Doing so may result in death or
serious injury due to electric
shock.
■To prevent damage or fire
●Make sure bulbs are fully
seated and locked.
●Check the wattage of the bulb
before installing to prevent heat
damage.

4247-1. Essential information
7-1.Essential information
Press the switch.
All the turn signal lights will flash.
To turn them off, press the switch
once again.
■Emergency flashers
●If the emergency flashers are
used for a long time while the
engine is not operating, the bat-
tery may discharge.
●If any of the SRS airbags deploy
(inflate) or in the event of a strong
rear impact, the emergency flash-
ers will turn on automatically.
The emergency flashers will turn
off automatically after operating
for approximately 20 minutes. To
manually turn t he emergency
flashers off, press the switch
twice.
(The emergency flashers may not
turn on automatically depending
on the force of the impact and
conditions of the collision.)
1 Steadily step on the brake
pedal with both feet and
firmly depress it.
Do not pump the brake pedal
repeatedly as this will increase the
effort required to slow the vehicle.
2Shift the shift lever to N.
If the shift lever is shifted to N
3 After slowing down, stop the
vehicle in a safe place by the
road.
4 Stop the engine.
If the shift lever cannot be
shifted to N
3 Keep depressing the brake
pedal with both feet to reduce
vehicle speed as much as
possible.
4 To stop the engine, press and
hold the engine switch for 2
consecutive seconds or
Emergency flashers
The emergency flashers are
used to warn other drivers
when the vehicle has to be
stopped on the road due to
a breakdown, etc.
Operating instructions
If your vehicle has to
be stopped in an emer-
gency
Only in an emergency, such
as if it becomes impossible
to stop the vehicle in the
normal way, stop the vehicle
using the following proce-
dure:
Stopping the vehicle

4297-2. Steps to take in an emergency
7
When trouble arises
truck for the tire strapping
method.
In order to suppress vehicle
movement during transporta-
tion, set the parking brake and
turn the engine switch off.
Fluid leaks under the vehicle
(Water dripping from the air
conditioning after use is nor-
mal.)
 Flat-looking tires or uneven
tire wear
 Engine coolant temperature
gauge needle continually
points higher than normal
 Changes in exhaust sound
 Excessive tire squeal when
cornering
 Strange noises related to the
suspension system
 Pinging or other noises
related to the engine
 Engine missing, stumbling or
running roughly
 Appreciable loss of power
 Vehicle pulls heavily to one
NOTICE
■To prevent damage to the
vehicle during emergency
towing
Do not secure cables or chains to
the suspension components.
If you think something
is wrong
If you notice any of the fol-
lowing symptoms, your
vehicle probably needs
adjustment or repair. Con-
tact your Toyota dealer as
soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

4397-2. Steps to take in an emergency
7
When trouble arises
ger detection sensor may cause
the warning light to flash and the
warning buzzer to sound even if a
passenger is not sitting in the
seat.
●If a cushion is placed on the seat,
the sensor may not detect a pas-
senger, and the warning light may
not operate properly.
■SRS warning light
This warning light system monitors
the airbag sensor assembly, front
impact sensors, side impact sensors
(front), side impact sensors (front
door), side impact sensors (rear),
driver’s seat position sensor,
driver’s seat belt buckle switch, front
passenger occupant classification
system (ECU and sensors), “PASS
AIR BAG ON” indicator light, “PASS
AIR BAG OFF” indicator light, front
passenger’s seat belt buckle switch,
driver’s seat belt pretensioner, front
passenger’s seat be lt pretensioner
and force limiter, airbags, intercon-
necting wiring and power sources.
(  P.34)
■If the malfunction indicator
lamp comes on while driving
First check the following:
●Is the fuel t ank empty?
If it is, fill the f uel tank immediately.
●Is the fuel tank cap loose?
If it is, tighten it securely.
The light will go o ff after several
driving trips.
If the light does not go off even after
several trips, contact your Toyota
dealer as soon as possible.
■Electric power steering system
warning light (warning buzzer)
When the battery charge becomes
insufficient or the voltage temporar-
ily drops, the electric power steering
system warning light may come on
and the warning buzzer may sound.
■When the tire pressure warning
light comes on
Inspect the tires to check if a tire is
punctured.
If a tire is punctured: P. 4 4 6
If none of the tires are punctured:
Turn the engine switch off then turn
it to ON. Check if the tire pressure
warning light com es on or blinks.
If the tire pressure warning light
blinks for 1 minute then stays on
There may be a malfunction in the
tire pressure warning system. Have
the vehicle inspected by your Toyota
dealer immediately.
If the tire pressur e warning light
comes on
1 After the temperature of the tires
has lowered sufficiently, check
the inflation pressure of each tire
and adjust them to the specified
level.
2 If the warning light does not turn
off even after several minutes
have elapsed, check that the
inflation pressure of each tire is
at the specified level and perform
initialization. ( P.399)
If the warning light d oes not turn off
several minutes af ter the initializa-
tion has been performed, have the
vehicle inspected by your Toyota
dealer immediately.
■The tire pressure warning light
may come on due to natural
causes
The tire pressure warning light may
come on due to natural causes such
as natural air leaks and tire inflation
pressure changes caused by tem-
perature. In this ca se, adjusting the
tire inflation pressure will turn off the
warning ligh t (after a few minutes).
■When a tire is replaced with a
spare tire
Vehicles with a co mpact spare tire:
The compact spare tire is not
equipped with a tire pressure warn-
ing valve and tran smitter. If a tire