2021 TOYOTA TUNDRA key battery

4526-3. Do-it-yourself maintenance
Open the case cover using a
coin protected with tape, etc.,
and remove the depleted bat-
tery.
Insert a new battery with the “+”
terminal facing up.
Vehicles with a smart key system
Take out the mechanical key.
Remove the cover.
To prevent damage to the key,
cover the tip of the screwdriver with
a rag.
Remove the depleted battery.
Insert a new battery with the “+”ter-
minal facing up.
3
1
2
3

4536-3. Do-it-yourself maintenance
6
Maintenance and care
■Use a CR2016 (vehicles without a smart key system) or CR2032 (v ehicles
with a smart key system) lithium battery
● Batteries can be purchased at your Toyota dealer, local electri cal appliance
shops or camera stores.
● Replace only with the same or equivalent type recommended by the manu-
facturer.
● Dispose of used batteries according to local laws.
■ If the key battery is depleted
The following symptoms may occur:
●The smart key system (if equipped) and wireless remote control will not
function properly.
● The operational range will be reduced.
WARNING
■Removed battery a nd other parts
Keep away from children. These parts are small and if swallowed by a child,
they can cause choking. Failure to do so could result in death or serious
injury.
■ Certification for the lithium battery
CAUTION: RISK OF EXPLOSION IF BATTERY IS REPLACED BY AN
INCORRECT TYPE. DISPOSE OF USED BATTERIES ACCORDING TO
THE INSTRUCTIONS
NOTICE
■For normal operation after replacing the battery
Observe the following precautions to prevent accidents:
● Always work with dry hands.
Moisture may cause the battery to rust.
● Do not touch or move any other component inside the remote cont rol.
● Do not bend either of the battery terminals.

473
7When trouble arises
7-1. Essential informationEmergency flashers .......... 474
If your vehicle has to be stopped in
an emergency ................. 475
If the vehicle is trapped in rising water .................. 477 7-2. Steps to take in an emergency
If your vehicle needs to be towed ......................... 478
If you think something is wrong .............................. 483
Fuel pump shut off system ............................ 484
If a warning light turns on or a warning buzzer
sounds ............................ 485
If a warning message is displayed......................... 493
If you have a flat tire.......... 506
If the engine will not start ................................. 521
If the electronic key does not operate
properly (vehicles with
a smart key system) ........ 523
If the vehicle battery is discharged ...................... 525
If your vehicle overheats ... 529
If the vehicle becomes stuck ............................... 532

5037-2. Steps to take in an emergency
7
When trouble arises
OnceContin-
uous
An attempt was made to exit
the vehicle with the electronic
key and lock the doors without
first turning the engine switch
off when the shift lever was in
P.
Turn the engine switch
off and lock the doors
again.
Once
The electronic key is not
detected when an attempt is
made to start the engine.
Start the engine with the
electronic key present.
9 times
An attempt was made to drive
when the electronic key was
not inside the vehicle.
Confirm that the elec-
tronic key is inside the
vehicle.
Contin-
uous
An attempt was made to lock
the doors using the smart key
system while the electronic
key was still inside the vehicle.
Retrieve the electronic
key from the vehicle and
lock the doors again.
OnceContin-
uous
An attempt was made to lock
either front door by opening a
door and putting the inside
lock button into the lock posi-
tion, then closing the door with
the electronic key still inside
the vehicle.
Retrieve the electronic
key from the vehicle and
lock the doors again.
Once
The electronic key has a low
battery.
Replace the electronic
key battery. ( P. 451)
Interior
buzzerExterior buzzerWarning messageDetails/Actions
Turn Power OFF
Key Not Detected
(Flashes)
Key Not Detected
(Flashes)
Key Not Detected
(Flashes)
Key Detected in Vehicle
(Flashes)
Key Detectedin Vehicle
(Flashes)
Key Battery Low

521
7
When trouble arises
7-2. Steps to take in an emergency
If the engine will not star t
One of the following may be the cause of the problem:
● There may not be sufficient f uel in the vehicle’s tank.
Refuel the vehicle.
● The engine may be flooded.
Try to restart the engine again following correct starting proc edures.
(  P. 217)
● There may be a malf unction in the engine immobilizer system.
(  P. 8 5 )
One of the following may be the cause of the problem:
● The battery may be discharged. ( P. 525)
● The battery terminal connecti ons may be loose or corroded.
The engine starting system may be malfunctioning due to an elec trical
problem such as an open circuit or a blown fuse. However, an in terim
measure is available to start the engine. ( P. 522)
If the engine will not start eve n though correct starting proce -
dures are being followed ( P. 217), consider each of the follow-
ing points.
The engine will not start even t hough the starter motor operates
normally.
The starter motor turns over slowly, the interior lights and he ad-
lights are dim, or the horn does not sound or sounds at a low
volume.
The starter motor does not turn over (vehicles with a smart key
system)

5227-2. Steps to take in an emergency
One of the following may be the cause of the problem:
● One or both of the battery t erminals may be disconnected.
● The battery may be discharged. ( P. 525)
Contact your Toyota dealer if the problem cannot be repaired, o r if repair
procedures are unknown.
When the engine does not start, the following steps can be used as an
interim measure to start the engine if the engine switch is fun ctioning
normally:
Set the parking brake.
Shift the shift lever to P.
Turn the engine switch to ACC.
Press and hold the engine switch for about 15 seconds while
depressing the brake pedal firmly.
Even if the engine can be start ed using the above steps, the sy stem
may be malfunctioning. Have the vehicle inspected by your Toyot a
dealer.
The starter motor does not turn over, the interior lights and h ead-
lights do not turn on, o r the horn does not sound.
Emergency start function (vehicles with a smart key system)
1
2
3
4

523
7
When trouble arises
7-2. Steps to take in an emergency
If the electronic key does not operate
properly (vehicles with a smar t key system)
Use the mechanical key (P. 122)
in order to perform the following
operations:
Locks all the doors
Unlocks all the doors
Turning the key rearward unlocks
the driver’s door. Turning the key
once again unlocks the other
doors.
Ensure that the shift lever is in P and depress the brake pedal.
Touch the Toyota emblem side
of the electronic key to the
engine switch.
If any of the doors is opened or
closed while the key is being
touched to the switch, an alarm will
sound to indicate that the start
function cannot detect the key.
Press the engine switch.
In the event that the engine still cannot be started, contact your Toyota
dealer.
If communication between the electronic key and vehicle is
interrupted ( P. 142) or the electronic key cannot be used
because the battery is depleted, the smart key system and wire-
less remote control cannot be used. In such cases, the doors
can be opened and the engine c an be started by following the
procedure below.
Locking and unlocking the doors
1
2
Starting the engine
1
2
3

5247-2. Steps to take in an emergency
■Stopping the engine
Shift the shift lever to P and press the engine switch as you normally do when
stopping the engine.
■ Replacing the key battery
As the above procedure is a temporary measure, it is recommende d that the
electronic key battery be replaced immediately when the battery is depleted.
( P. 451)
■ Changing engine switch modes
Within 10 seconds of the buzzer sounding, release the brake ped al and press
the engine switch.
The engine does not start and modes will be changed each time t he switch is
pressed. ( P. 220)