OPERATION
The Tire Pressure Monitoring (TPM) system uses
radio and sensor technology to monitor tire air pres-
sure levels. Sensors, mounted to each road wheel as
part of the valve stem, transmit a low frequency indi-
cating their individual pressure to a receiver located
in the Wireless Control Module (WCM) portion of the
Sentry Key Remote Electronic Entry Module
(SKREEM). These transmissions occur approximately
once every minute at speeds over 20 mph (32 km/h).
The Tire Pressure Monitoring system remains active
even if no tire pressure related message is displayed.
The sensors lay dormant (Park Mode), then wake
and start transmitting (Drive Mode) when the vehicle
first reaches speeds over 20 mph (32 km/h). Once the
wheels stop rotating for a period of approximately 30
minutes, the sensors shut down until again awaken.
Although not transmitting as when in Drive Mode,
while in Park Mode, the sensors still transmit
approximately once every 13 hours to let the receiver
know air pressure status at that time.
The receiver only receives information from the
four rotating tires. A fifth sensor may be located in
the spare tire wheel, depending on vehicle options.
Although this fifth sensor may be present, it does not
broadcast any information because it does not rotate.
When the system detects that a tire is going low,
below the Low Pressure (lamp) ON Threshold (See
following table), the driver is alerted to the situation.
The Base system illuminates an indicator lamp,
warning the driver of a pressure issue and sounds an
audible chime. In equipped with the Premium sys-
tem, the information is also displayed on the Elec-
tronic Vehicle Information Center (EVIC).
Once pressure in the suspect tire raises above the
Low Pressure (lamp) OFF Threshold, the lamp will
go out and the system returns to normal.
TPM THRESHOLD PRESSURES
DESCRIPTION SPECIFICATION
Placard Pressure (Cold) 36 PSI (248 kPa)
Low Pressure OFF Threshold 33 PSI (228 kPa)
Low Pressure ON Threshold 28 PSI (193 kPa)
SENSOR - TPM
DESCRIPTION
On vehicles equipped with Tire Pressure Monitor-
ing, one tire pressure sensor is mounted to each road
wheel (Fig. 18), and depending on factory wheel
options, a sensor may be located in the spare tire
wheel. Both aluminum and steel wheels are used in
this system, although sensors for one type wheel can-
not be used in the other type wheel.Each sensor has an internal battery that lasts up
to 10 years. The battery is not serviceable. At the
time of battery failure, the sensor must be replaced.
The serviceable components of the tire pressure sen-
sor are:
²Sensor-To-Wheel Grommet
²Valve Stem Cap
²Valve Stem Core
Valve stem caps and cores are specifically designed
for the tire pressure monitoring sensors. Although
similar to standard valve stem caps and cores, they
are different.
CAUTION: Do not use a standard valve stem cap or
core in a tire pressure sensor. Always use the orig-
inal equipment style sensor cap and core.
CAUTION: Do not reuse the Sensor-To-Wheel Grom-
met. Always use a new grommet when installing a
pressure sensor and properly torque the sensor
nut.
CAUTION: Do not attempt to install a tire pressure
sensor in an aftermarket wheel. Use only in original
style factory wheels.
OPERATION
The battery operated tire pressure sensors lay dor-
mant (Park Mode), then wake and start transmitting
(Drive Mode) when the vehicle first reaches speeds
over 20 mph (32 km/h). Once the wheels stop rotat-
ing for a period of approximately 30 minutes, the
sensors shut down until again awaken. Although not
transmitting as when in Drive Mode, while in Park
Mode, the sensors still transmit approximately once
every 13 hours to let the receiver know air pressure
status at that time.
Each sensor transmits tire pressure data approxi-
mately once every minute. Each sensor's (transmit-
ter) broadcast is uniquely coded so that the wireless
control module (WCM) can monitor the state of each
of the sensors on the four rotating road wheels. The
WCM (located in the SKREEM) automatically learns
and stores the sensor's ID while driving after a sen-
sor has been replaced. There is no retraining neces-
sary.
The receiver only receives information from the
four rotating tires. A fifth sensor may be located in
the spare tire wheel, depending on vehicle options.
Although this fifth sensor may be present, it does not
broadcast any information because it does not rotate.
For additional information, refer to Appropriate
Diagnostic Information.
22 - 10 TIRES/WHEELSRS
TIRE PRESSURE MONITORING (Continued)
