snow chains TOYOTA SIENNA 2007 Service Repair Manual

TIRE AND WHEEL – TIRE PRESSURE WARNING SYSTEMTW–17
TW
3. WHEN TIRE PRESSURE WARNING LIGHT IS LIT
(a) When the tire pressure warning light does not go off,
or when it comes on during driving, check tire
pressure. If the tire pressure warning light comes on
within several hours after adjusting the tire
pressure, the tire may have a slow air leak.
(b) Under the following conditions, the system may not
function properly.
• 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 large amount of snow or ice is stuck to the
vehicle, especially onto the wheels and around
the wheel houses.
• The ID of the tire pressure warning valve and
transmitter has not been registered with the
ECU.
• A film or window tint that may interfere with radio
waves is attached on the glass.
• The battery of the sensor has been depleted.
• The tires without tire pressure warning valve and
transmitter are used.
• Tire chains are used.
• The use of non-genuine wheels may result in the
system failure or air-leak.
• Depending on the tire type, the system may not
function properly even though the specified
wheels are used.
(c) After removing and installing the ECU or a sensor,
check for a diagnostic trouble code and verify that it
is a normal code.
4. FUNCTION OF COMPONENTS
5. TIRE PRESSURE WARNING RESET SWITCH
• By operating the tire pressure warning reset switch,
the tire pressure warning ECU can be set to issue a
warning at an inflation pressure that corresponds to
the standard pressure of tires.
Therefore, the dealer must set the warning threshold
to the proper value in order to comply with the local
regulations.
Components Function
Tire pressure warning valve and transmitterCombined 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 warning antenna and receiverReceives and transmits a necessary signal from the transmitter to the tire pressure
warning ECU.
Tire pressure warning ECUReceives a signal from the receiver and identifies it as vehicle's own signal. If the
measured value is equal to or lower than the specified value, it transmits a signal so
that the tire pressure warning light on the combination meter comes on.
Tire pressure warning lightLocated 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 the change of the standard pressure