TPWS - Tire Pressure Monitor

[navylife59]

DESCRIPTION OF SYSTEM
(a) A tire pressure warning valve and transmitter is
equipped with a tire pressure sensor and a
transmitter and is installed in a tire wheel assembly.
The sensor measures the tire pressure. The
measured value and transmitter ID are transmitted
to the tire pressure warning antenna and receiver on
the body as radio waves and then sent to the tire
pressure warning ECU from the tire pressure
warning antenna and 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 warning ECU,
the warning light on the combination meter comes
on.
• For the differences in the air pressure settings by
the type of tires, a tire pressure warning reset
switch has been adopted.



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 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 tires 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 in the ON position. After the
initialization process has started, the warning light
blinks 3 times (1 second on, 1 second off).
• During initialization, the tire pressure warning valve
and transmitter measures the inflation pressure of the
tires, and registers the signals that are transmitted
into the tire pressure warning ECU at a frequency of
once per minute. The initialization process is
completed when signals from the all tires have been
received.








Tire Pressure Monitors - Each has a unique ID code that is registered to the vehicle's Tire Pressure ECU. This is accomplished via the Toyota Intelligent Tester.



Note: This wiring schematic is for 2007-up models. Uncertain if the same pinout is for the 2005-2006 models.

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 battery of the sensor has been depleted.
• The tires without tire pressure warning valve and
transmitter are used.
• Tire chains are used.
• If any wheels other than the specified ones are
used, the system may not function properly
because interference may prevent the radio
waves from being correctly transmitted from the
tire pressure warning valve and transmitter.
• Depending on the tire type, the system may not
function properly even though the specified
wheels are used.
(c) The average usage life of the grommet of the tire
pressure warning valve and transmitter is
approximately 5 years, at which time it must be
replaced.
Re-tighten the valve nut if the valve is leaking air,
although it is less than 5 years old and there is no
problem with grommets.
(d) After removing and installing the ECU or a sensor,
check for a diagnostic trouble code and verify that it
is a normal code.