Toyota Sequoia (2005). Manual - part 251

DIDJV–01

F19126

Combination meter assy
(Vehicle speed signal)

Tire pressure monitor receiver assy

Combination meter assy 
(Tire pressure warning lamp)

Tire 
Pressure 
Monitor 
ECU

: Radio signal

Tire Pressure Sensor
(Tire pressure monitor valve
sub–assy) (FR LH)

Tire Pressure Sensor
(Tire pressure monitor valve
sub–assy) (FR RH)

Tire Pressure Sensor
(Tire pressure monitor valve
sub–assy) (RR LH)

Tire Pressure Sensor
(Tire pressure monitor valve
sub–assy) (RR RH)

Tire Pressure Sensor
(Tire pressure monitor valve
sub–assy) (SPARE)

DLC3

Tire pressure warning reset switch

–

DIAGNOSTICS

TIRE PRESSURE WARNING SYSTEM

DI–799

993

SYSTEM DIAGRAM

DIDJW–01

F19887

Tire Pressure Monitor Valve Sub–assy

Tire Pressure 
Warning Reset
Switch

Tire Pressure 

Monitor ECU

Meter

DLC3

Tire Pressure Monitor Valve Sub–assy

Tire Pressure Monitor Receiver Assy

DI–800

–

DIAGNOSTICS

TIRE PRESSURE WARNING SYSTEM

994

SYSTEM DESCRIPTION

1.

DESCRIPTION OF SYSTEM

(a)

A tire pressure monitor valve sub–assy equipped with a tire pressure sensor and a transmitter and is
installed in a tire wheel assy. The sensor measures the tire pressure and the measured value and
transmitter ID are transmitted to the tire pressure monitor receiver assy on the body as radio waves
and then sent to the tire pressure monitor ECU from the tire pressure monitor receiver. If the transmitter
ID has already been registered, the ECU compares the measured air pressure value with the standard
value. When the value is less than the standard value registered in the tire pressure monitor ECU, the
warning lamp on the combination meter comes on.

To address the differences in the air pressure settings by the type of tires, or the differences in
pressure between the front and rear tires, a tire pressure warning reset switch has been newly
adopted.

Along with the adoption of the tire pressure warning reset switch, the warning operation has been
changed.

TPWS transmitters with different bending angles as the tire pressure monitor valve sub–assy
have been provided for steel wheels with center ornaments. (They are not interchangeable with
aluminum wheels or steel wheels with full wheel caps.)

2.

WHEN TIRE PRESSURE WARNING LAMP IS LIT

(a)

When the warning lamp does not go off, or when it comes on during driving, check tire pressure. If the
warning lamp is lit even though the tire pressure is correctly adjusted, the tire could be punctured.

(b)

Under the following conditions, the system may not function properly.

The areas, facilities or devices that use similar radio frequencies are located in the vicinity of the
vehicle.

A radio device of similar frequency is used in the vehicle.

A lot of snow or ice is stuck to the vehicle, especially onto the wheels and around the wheel
houses.

The battery of the sensor has been depleted.

The tires without tire pressure monitor valve sub–assy are used.

Tire chains are used.

–

DIAGNOSTICS

TIRE PRESSURE WARNING SYSTEM

DI–801

995

When the spare tire is not within the receivable range of the electric wave, a signal may not be
received because spare tires are fixed. Accordingly, the system may not function properly. If
there is a possibility that the TPWS system does not receive a signal from the spare tire, rotate
the tire 90

°.

HINT:

If any other wheels than the specified ones are used, the system may not function properly because
the radio waves are differently transmitted from the tire pressure sensor.

Depending on the tire type, the system may not function properly even though the specified wheels
are used.

(c)

The average use life of the grommet of the tire pressure monitor valve sub–assy is approximately 5
years, at which time it must be replaced.

(d)

After removing and installing the ECU or a sensor, output a diagnosis code and check that it is a normal
code.

3.

FUNCTION OF COMPONENTS

Components

Function

Tire pressure monitor valve sub–assy

Combined as a single unit with a disc wheel air valve, it measures tire pressure and

temperature and transmits an ID number for measurement value and identification.

Built–in the battery.

Tire pressure monitor receiver assy

Receives and transmits a necessary signal from the transmitter to the tire pressure

monitor ECU.

Tire pressure monitor ECU

Receives the signal from the receiver and identifies it as vehicle’s own signal. If the

measurement value is equal to or lower than the specified value, it transmits a sig-

nal so that the air pressure warning lamp on the combination meter comes on.

Tire pressure warning lamp

Located in the combination meter, it informs the driver of lowered tire air pressure

and system failure.

Tire pressure warning reset switch

Enters the initialization mode for tire or wheel replacement, or tire rotation

4.

TIRE PRESSURE WARNING RESET SWITCH

By operating the tire pressure warning reset switch, the tire pressure monitor ECU can be set to issue
a warning at an inflation pressure that corresponds to the type of tires. Therefore, the dealer must set
the warning threshold to the proper value in order to comply with the local regulations.

Operate the tire pressure warning reset switch only after the inflation pressures of all 5 tires (including
the spare) have been adjusted on the vehicle.

To initialize the system, press and hold the tire pressure warning reset switch for 3 seconds or longer
with the ignition switch ON. After the system has been initialized, the warning lamp blinks 3 times (1
second ON, 1 second OFF).

During initialization, the tire pressure monitor valve sub–assy measures the inflation pressure of the
tires, and registers the signals that are transmitted into the tire pressure monitor ECU at a frequency
of one per minute. The initialization process is completed when the signals from the 5 tires have been
received.

The initialization process is canceled if the ignition switch is turned OFF during initialization. To initialize
again, the tire pressure warning reset switch must be pressed again. For this reason, once the tire pres-
sure warning reset switch has been pressed, turning OFF the ignition switch is not recommended for
a minimum of 20 minutes.

DIDJX–01

DI–802

–

DIAGNOSTICS

TIRE PRESSURE WARNING SYSTEM

996

HOW TO PROCEED WITH TROUBLESHOOTING

The hand–held tester can be used at steps 3, 7 and 9.

1

Vehicle Brought to Work Shop

NEXT

2

Customer Problem Analysis (See page 

DI–804

)

NEXT

3

DTC Check and Clear (See page 

DI–820

)

DTC is output: Go to step 4

DTC is not output: Go to step 5

4

DTC Chart (See page 

DI–825

)

Go to step 7

5

Problem Symptom Confirmation

Symptom does not occur: Symptom simulation
(See page 

IN–24

)

Symptom occurs: Go to step 6