2020 TOYOTA TUNDRA wiring

2184-2. Driving procedures
■When the steering lock cannot be released
■ Key reminder function
A buzzer sounds if the driver’s door is opened while the engine switch is in
ACC or OFF to remind you to remove the key. When starting the engine, the engine
switch may seem stuck in the OFF. To
free it, turn the key while turning the steer-
ing wheel slightly left and right.
WARNING
■ When starting the engine
Always start the engine while sitting in the driver’s seat. Do not depress the
accelerator pedal while starting the engine under any circumsta nces.
Doing so may cause an accident resulting in death or serious in jury.
■ Caution while driving
Do not turn the engine switch to OFF while driving. If, in an e mergency, you
must turn the engine off while the vehicle is moving, turn the engine switch
only to ACC to stop the engine. An accident may result if the e ngine is
stopped while driving. ( P. 473)
NOTICE
■To prevent battery discharge
Do not leave the engine switch in ACC or ON for long periods of time with-
out the engine running.
■ When starting the engine
● Do not crank the engine for more than 30 seconds at a time. This may
overheat the starter and wiring system.
● Do not race a cold engine.
● If the engine becomes difficult to start or stalls frequently, have your vehi-
cle checked by your Toyota dealer immediately.

4046-1. Maintenance and care
■Caring for leather areas
Toyota recommends cleaning the interior of the vehicle at least twice a year to
maintain the quality of the vehicle’s interior.
■ Shampooing the carpets
There are several commercial foaming-type cleaners available. U se a sponge
or brush to apply the foam. Rub in overlapping circles. Do not use water.
Wipe dirty surfaces and let them dry. Excellent results are obt ained by keep-
ing the carpet as dry as possible.
■ Seat belts
Clean with mild soap and lukewarm water using a cloth or sponge . Also
check the belts periodically for excessive wear, fraying or cut s.
■ When cleaning the carpeted portions of the console box, etc.
If a strong adhesive tape is used, there is a possibility that the surface of the
carpet could be damaged.
WARNING
■ Water in the vehicle
● Do not splash or spill liquid in the vehicle.
Doing so may cause electrical components, etc., to malfunction or catch
fire.
● Do not get any of the SRS components or wiring in the vehicle i nterior wet.
( P. 42)
An electrical malfunction may cause the airbags to deploy or no t function
properly, resulting in death or serious injury.
■ Cleaning the interior (esp ecially instrument panel)
Do not use polish wax or polish cleaner. The instrument panel m ay reflect
off the windshield, obstructing the driver’s view and leading t o an accident,
resulting in death or serious injury.

4536-3. Do-it-yourself maintenance
6
Maintenance and care
Check if the fuse is blown.Normal fuse
Blown fuse
Type A and B:
Replace the blown fuse with a new fuse of an appropriate ampera ge rat-
ing. The amperage rating can be found on the fuse box cover.
Type C:
Contact your Toyota dealer.
■ After a fuse is replaced
●If the lights do not turn on even after the fuse has been repla ced, a bulb may
need replacement. ( P. 455)
● If the replaced fuse blows again, have the vehicle inspected by your Toyota
dealer.
■ If there is an overload in a circuit
The fuses are designed to blow, protecting the wiring harness f rom damage.
4
1
2
Ty p e AType B
Ty p e C

4877-2. Steps to take in an emergency
7
When trouble arises
■SRS warning light
This warning light system monitors the airbag sensor assembly, front impact
sensors, side impact sensors (front door), side impact sensors (rear), driver’s
seat position sensor, driver’s seat belt buckle switch, front passenger occu-
pant classification system (ECU and sensors), “AIR BAG ON” indi cator light,
“AIR BAG OFF” indicator light, front passenger’s seat belt buck le switch, seat
belt pretensioners assemblies, airbags, interconnecting wiring and power
sources. ( P. 42)
■ Front passenger detection sensor, seat belt reminder and warnin g
buzzer
● If luggage is placed on the front passenger seat, the front pas senger detec-
tion sensor may cause the warning light to flash and the warnin g 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 passenger,
and the warning light may not operate properly.
■ If the malfunction indicator lamp comes on while driving
First check the following:
●Is the fuel tank empty?
If it is, fill the fuel tank immediately.
● Is the fuel tank cap loose?
If it is, tighten it securely.
The light will go off after several driving trips.
If the light does not go off even after several trips, contact your Toyota dealer
as soon as possible.
■
When the tire pressure warning light comes on
Check the tire inflation pressure and adjust to the appropriate level. Push-
ing the tire pressur e warning reset switch will not turn off the tire pressure
warning light.

4997-2. Steps to take in an emergency
7
When trouble arises
*: Refer to the separate “Scheduled Maintenance Guide” or “Owner’s Manual
Supplement” for the maintenance interval applicable to your veh icle.
■Warning message in radar cruise mode (if equipped)
In the following cases, the warning message may not be displaye d even if
vehicle-to-vehicle distance decreases:
● When your vehicle and the vehicle ahead are traveling at the sa me speed or
the vehicle ahead is traveling more quickly than your vehicle
● When the vehicle ahead is traveling at a very low speed
● Immediately after cruise control speed is set
● At the instant the accelerator pedal is depressed
■
Conditions that the tire pressure warning system may not functi on
properly
 P. 4 3 2
Indicates that an internal switch failure of trailer
brake control system, an over current detected by
trailer brake control system.
 Have the vehicle inspected by your Toyota
dealer immediately.
Indicates that an internal microprocessor error,
output circuit to trailer brakes unintended current,
or manual brake output slider is stuck or broken
 Have the vehicle inspected by your Toyota
dealer immediately.
Indicates that the output circuit has reverse volt-
age, or the internal trailer brake control system
temperature is too high.
Check trailer wiring issue, check trailer
connection. If there is still a problem, have
the vehicle inspected by your Toyota dealer
immediately.
Warning messageDetails/Actions
Trailer Brake Error.
If Towing,
Come to a Safe Stop
Contact dealer.
Trailer Wiring,
Type, or Connection
fault.
See Owner’s manual.