2021 TOYOTA 4RUNNER ECU

1814-1. Before driving
4
Driving
4RUNNER (U)
WARNING
Observe the following precautions.
Failure to do so may result in death or serious injury.
■If you hear a squealing or scrap ing noise (brake pad wear limit indica-
tors)
Have the brake pads checked and replaced by your Toyota dealer as soon
as possible.
Rotor damage may result if the pads are not replaced when needed.
It is dangerous to drive the vehicle when the wear limits of the brake pads
and/or those of the brake discs are exceeded.
■ When the vehicle is stopped
● Do not race the engine.
If the vehicle is in any gear other than P or N, the vehicle may accelerate
suddenly and unexpectedly, causing an accident.
● In order to prevent accidents due to the vehicle rolling away, always keep
depressing the brake pedal while the engine is running, and app ly the
parking brake as necessary.
● If the vehicle is stopped on an incline, in order to prevent ac cidents caused
by the vehicle rolling forward or backward, always depress the brake pedal
and securely apply the parking brake as needed.
● Avoid revving or racing the engine.
Running the engine at high speed while the vehicle is stopped m ay cause
the exhaust system to overheat, which could result in a fire if combustible
material is nearby.

1834-1. Before driving
4
Driving
4RUNNER (U)
WARNING
Observe the following precautions.
Failure to do so may result in death or serious injury.
■When taking a nap in the vehicle
Always turn the engine off. Otherwise, if you accidentally move the shift
lever or depress the accelerator pedal, this could cause an acc ident or fire
due to engine overheating. Additionally, if the vehicle is park ed in a poorly
ventilated area, exhaust gases may collect and enter the vehicl e, leading to
death or a serious health hazard.
■ When braking
● When the brakes are wet, drive more cautiously.
Braking distance increases when the brakes are wet, and this ma y cause
one side of the vehicle to brake differently than the other sid e. Also, the
parking brake may not securely hold the vehicle.
● If the brake booster device does not operate, do not follow oth er vehicles
closely and avoid hills or shar p turns that require braking.
In this case, braking is still possible, but the brake pedal sh ould be
depressed more firmly than usual. Also, the braking distance wi ll increase.
● Do not pump the brake pedal if the engine stalls.
Each push on the brake pedal uses up the reserve for the power-assisted
brakes.
● The brake system consists of 2 individual hydraulic systems; if one of the
systems fails, the other will still operate. In this case, the brake pedal
should be depressed more firmly than usual and the braking dist ance will
increase.
If this happens, do not continue to drive the vehicle. Have you r brakes
fixed immediately.

1864-1. Before driving
4RUNNER (U)
Cargo and luggage
Take notice of the following information about storage precau-
tions, cargo capacity and load:● Stow cargo and luggage in the luggage compartment whenever
possible.
● Be sure all items are secured in place.
● To maintain vehicle balance while driving, position luggage evenly
within the luggage compartment.
● For better fuel economy, do no t carry unnecessary weight.

1894-1. Before driving
4
Driving
4RUNNER (U)
■When using the roof rails (if equipped)
●To use the roof rails as a roof luggage
carrier, you must fit the roof rails with
two or more genuine Toyota cross rails
or their equivalent.
●When there is no luggage on the roof
luggage carrier Toyota recommends
that the front and rear cross rails be
secured in the positions indicated in
the illustration. This may reduce wind
noise while driving.
WARNING
■Things that must not be carried in the luggage compartment
The following things may cause a fire if loaded in the luggage compart-
ment:
●Receptacles containing gasoline
●Aerosol cans
■Storage precautions
Observe the following precautions.
Failure to do so may prevent the pedals from being depressed pr operly,
may block the driver’s vision, or may result in items hitting t he driver or
passengers, possibly causing an accident.
●Stow cargo and luggage in the luggage compartment whenever poss i-
ble.
●Do not stack cargo and luggage in the luggage compartment highe r
than the seatbacks.
●Do not place cargo or luggage in or on the following locations.
• At the feet of the driver
• On the front passenger or rea r seats (when stacking items)
• On the instrument panel
• On the dashboard
●Secure all items in the occupant compartment.
●When you fold down the rear seats, long items should not be pla ced
directly behind the front seats.
●Never allow anyone to ride in the luggage compartment. It is no t
designed for passengers. They should ride in their seats with t heir seat
belts properly fastened. Otherwise, they are much more likely t o suffer
death or serious bodily injury, i n the event of sudden braking, sudden
swerving or an accident.
Roof rails Cross rails

1904-1. Before driving
4RUNNER (U)
WARNING
■Capacity and distribution
●Do not exceed the maximum axle weight rating or the total vehicle
weight rating.
●Even if the total load of occupant’s weight and the cargo load is less
than the total load capacity, d o not apply the load unevenly. I mproper
loading may cause deterioration of steering or braking control which
may cause death or serious injury.
■When loading cargo on the roof luggage carrier
Observe the following precautions:
●Place the cargo so that its wei ght is distributed evenly betwee n the
front and rear axles.
●If loading long or wide cargo, n ever exceed the vehicle overall length
or width. (
P. 5 2 0)
●Before driving, make sure the cargo is securely fastened on the roof
luggage carrier.
●Loading cargo on the roof lugga ge carrier will make the center of grav-
ity of the vehicle higher. Avoid high speeds, sudden starts, sh arp turns,
sudden braking or abrupt maneuvers, otherwise it may result in loss of
control or vehicle rollover due to failure to operate this vehi cle correctly
and result in death or serious injury.
●If driving for a long distance, on rough roads, or at high spee ds, stop
the vehicle now and then during the trip to make sure the cross rails
are fixed securely and that the cargo remains in its place.
●Do not exceed 120 lb. (54 kg) cargo weight on the roof luggage carrier.
NOTICE
■When loading cargo on the roof luggage carrier
Be careful not to scratch the surface of the moon roof (if equipped).

2044-1. Before driving
4RUNNER (U)■
Before towing
Check that the following conditions are met:
●Ensure that your vehicle’s tires are properly inflated. ( P. 528)
● Trailer tires are inflated according to the trailer manufacture r’s recommen-
dation.
● All trailer lights work as required by law.
● All lights work each time you connect them.
● The trailer ball is set at the proper height for the coupler on the trailer.
● The trailer is level when it is hitched.
Do not drive if the trailer is not level, and check for imprope r tongue weight,
overloading, worn suspension, or other possible causes.
● The trailer cargo is securely loaded.
● The rear view mirrors conform to all applicable federal, state/provincial or
local regulations. If they do not, install rear view mirrors ap propriate for tow-
ing purposes.
■ Break-in schedule
If your vehicle is new or equipped with any new power train com ponents
(such as an engine, transmission, differential or wheel bearing ), Toyota rec-
ommends that you do not tow a trailer until the vehicle has bee n driven for
over 500 miles (800 km).
After the vehicle has been driven for over 500 miles (800 km), you can start
towing. However, for the next 500 miles (800 km), drive the veh icle at a speed
of less than 45 mph (72 km/h) when towing a trailer, and avoid full throttle
acceleration.
■ Maintenance
●If you tow a trailer, your vehicle will require more frequent m aintenance due
to the additional load. (See “Scheduled Maintenance Guide” or “ Owner’s
Manual Supplement”.)
● Retighten the fixing bolts of the towing ball and bracket after approximately
600 miles (1000 km) of trailer towing.
■ If trailer sway occurs
One or more factors (crosswinds, passing vehicles, rough roads, etc.) can
adversely affect handling of your vehicle and trailer, causing instability.
● If trailer swaying occurs:
• Firmly grip the steering wheel. Steer straight ahead.
Do not try to control trailer swaying by turning the steering w heel.
• Begin releasing the accelerator pedal immediately but very gra dually to
reduce speed.
Do not increase speed. Do not apply vehicle brakes.
If you make no extreme correction with the steering or brakes, your vehicle
and trailer should stabilize. (if enabled, Trailer Sway Control can also help to
stabilize the vehicle and trailer.)

2064-1. Before driving
4RUNNER (U)
WARNING
●Do not apply the brakes suddenly as you may skid, resulting in jackknifing
and loss of vehicle control. This is especially true on wet or slippery sur-
faces.
● Do not exceed the trailer hitch assembly weight, gross vehicle weight,
gross axle weight and trailer tongue weight capacities.
● Do not use cruise control when towing.
● Slow down and downshift before descending steep or long downhill
grades. Do not make sudden downshifts while descending steep or long
downhill grades.
● Vehicle-trailer instability is more likely on steep long downhi lls. Before
descending steep or long downhill grades, slow down and downshi ft. Do
not make sudden downshifts when descending steep or long downhi ll
grades. Avoid holding the brake pedal down too long or applying the
brakes too frequently. This could cause the brakes to overheat and result
in reduced braking efficiency.
■ Hitch
Trailer hitch assemblies have different weight capacities estab lished by the
hitch manufacturer. Even though the vehicle may be physically capable of
towing a higher weight, the operator must determine the maximum weight
rating of the particular hitch assembly and never exceed the ma ximum
weight rating specified for the trailer-hitch. Exceeding the ma ximum weight
rating set by the trailer-hitch manufacturer can cause an accid ent resulting
in death or serious personal injuries.
■ When towing a trailer
Toyota recommends trailers with brakes that conform to any appl icable fed-
eral and state/provincial regulations.
● If the gross trailer weight exceeds unbraked TWR, trailer brake s are
required. Toyota recommends trailers with brakes that conform t o all appli-
cable federal and state/provincial regulations.
● Never tap into your vehicle’s hydraulic system, as this will lo wer the vehi-
cle’s braking effectiveness.
● Never tow a trailer without using a safety chain securely attac hed to both
the trailer and the vehicle. If damage occurs to the coupling u nit or hitch
ball, there is danger of the trailer wandering into another lan e.

2154-2. Driving procedures
4
Driving
4RUNNER (U)■
If the engine does not start
●The engine immobilizer system may not have been deactivated. ( P. 76)
Contact your Toyota dealer.
● Check that the shift lever is securely set in P. The engine may not start if the
shift lever is displaced out of P.
■ Steering lock
After turning the engine switch off and opening and closing the doors, the
steering wheel will be locked due to the steering lock function. Operating the
engine switch again automatically cancels the steering lock.
■ When the steering lock cannot be released
■ Steering lock motor overheating prevention
To prevent the steering lock motor from overheating, the motor may be sus-
pended if the engine is turned on and off repeatedly in a short period of time.
In this case, refrain from operating the engine. After about 10 seconds, the
steering lock motor will resume functioning.
■ When a message requesting the smart key system be inspected is dis-
played on the multi-information display
The system may be malfunctioning. Have the vehicle inspected by your
Toyota dealer immediately.
■ If the electronic key battery is depleted
P. 443
■ Operation of the engine switch
If the switch is not pressed shortly and firmly, the engine swi tch mode may
not change or the engine may not start. When the steering lock cannot be
released, “Push the engine switch while
turning the steering wheel in either direc-
tion” will be displayed on the multi-infor-
mation display.
Press the engine switch shortly and firmly
while turning the steering wheel left and
right.