Wheel Unit; Construction; Operation; Sensing Function - Mazda 2006 MX-5 Service Highlights

WHEEL UNIT CONSTRUCTION/OPERATION

Construction

• The wheel unit is installed to the rim of each wheel with a nut. It monitors air pressure, temperature and
acceleration of the tire, and sends the data as RF signals.
• The wheel unit also serves as a tire valve.

Operation

• The wheel unit operates on a built-in battery, and regularly sends tire data as RF signals. The data it sends is
retrieved using a sensing function that monitors tire pressure and temperature, and a self-diagnostic function
that detects battery status and sensor malfunction.
• To maximize the life of the built-in battery, the unit uses the detected air pressure and acceleration to determine
vehicle conditions such as driving and long stops, and operates in a mode appropriate to vehicle conditions so
that battery consumption is minimized.
• Each wheel unit has its own identification code that is sent together with tire data and is used to verify which tire
has abnormal tire pressure. Therefore, when the wheel unit or the instrument cluster is replaced, the
identification codes must be configured.

Sensing Function

• The sensing function periodically monitors the following data and sends it to the keyless receiver.
— Tire pressure
— Tire temperature
— Tire acceleration
— Voltage of the built-in battery
• Intervals of tire data monitoring and data transmission to the keyless receiver differ depending on the
operational mode (varies according to vehicle conditions).

Self-diagnostic Function

• The self-diagnostic function continuously performs malfunction diagnosis for each sensing function item. If any
abnormality is found by the malfunction diagnosis, the data is sent to the keyless receiver.
End Of Sie

TIRE PRESSURE MONITORING SYSTEM (TPMS) OPERATION

• The instrument cluster monitors the tire pressure of each tire and the wheel units for abnormalities using the
received data. If any abnormality is found, it controls TPMS warning light, TPMS warning buzzer, flat tire
warning light and flat tire warning buzzer to alert and notify the driver.
• The instrument cluster controls the following functions based on the received data:
Function list
Identification code recognition function
Tire pressure determination/warning
function
02–12–8
WHEEL AND TIRES
• Recognizes whether received signals are from own wheel units.
• Compares received tire pressure data with preset values. If the pressure is
determined to be too low or to have flat tire, the instrument cluster alerts the
driver via the TPMS warning light and buzzer or flat tire warning light and
buzzer.

WHEEL UNIT

E5U021237140N01
E5U212ZW5005
E5U021267502N01