Jeep Liberty KJ. Manual - part 1272

optional wheel/tire sizes and significantly different tire placard pressures, the placard pressure value and the low-
pressure threshold value shall be re-programmable by the dealer to accommodate the customer selected wheel/tire
combinations recommended by DaimlerChrysler).

PREMIUM TIRE PRESSURE MONITORING

The tire pressure monitoring system is designed to operate without loss of function for all types of standard tire
constructions. (Function with different types of run flat tire constructions needs to be evaluated for each design). The
wheel sensor shall monitor tire pressure, air temperature inside the tire, wheel acceleration and the sensor internal
battery status for all four active road tires and the spare tire, if so equipped. The sensor will broadcast this infor-
mation, along with a unique 32 bit ID, to a central receiver circuit located inside the WCM. The information received
by the WCM will be decoded and stored in (RAM) memory in the WCM. The WCM will send bus messages to the
re-configurable display module to display the pressures of the four active road tires in vehicle position. The spare
tire pressure is monitored but it is not displayed.

If a

warning

fault

condition exists, the WCM will send a bus message request to display the text messages

and, when required, illuminate the yellow telltale.

Warnings

and

faults

are described in more detail below. If the

WCM detects a warning or fault condition at ignition key

it will wait ten seconds +/- 10% before sending the first

request to illuminate the yellow telltale and to display the text messages. This will assure that the display module
has concluded its bulb check period. The display module will request a chime once per ignition cycle for each

warning

fault

condition detected. A

warning

fault

condition will remain enabled until the problem causing

the condition is corrected and removed/reset

The WCM shall continuously monitor for the receipt of tire pressure RF message transmissions from the wheel
sensors during both the ignition key

and key

off

cycles. The wheel sensor ID’s and the location of each sen-

sor (e.g. Left Front, Right Front etc.) are stored in the WCM non-volatile memory during the initial Manufacturing
Plant Process, or during a service procedure, as required. The recommended

placard pressure

low-pressure

threshold

and Hysteresis Pressure Values for the tires installed on the vehicle, are stored in the WCM non-volatile

memory during the initial Manufacturing Plant Process, as described later in this document or during a service pro-
cedure as required. (Note: For vehicles with optional wheel/tire sizes and significantly different tire placard pres-
sures, the placard pressure value and the low-pressure threshold value shall be re-programmable by the dealer to
accommodate the customer selected wheel/tire combinations recommended by DaimlerChrysler).

DIAGNOSIS AND TESTING - TIRE PRESSURE MONITORING SYSTEM

All Tire Pressure Monitoring System Faults are specific to one location. If a

BATTERY LOW

SENSOR FAIL-

URE

fault is detected, the location will be displayed (Premium Systems). The appropriate sensor/transmitter can

then be replaced. If a single sensor/transmitter cannot be detected by the WCM, replace that sensor transmitter. If
none of the sensors/transmitters can be detected, refer to symptoms in the WCM section. For additional system
description and diagnosis, refer to Tire Pressure Monitoring in the Body Diagnostic manual.

SPECIFICATIONS

TORQUE CHART

TORQUE SPECIFICATIONS

DESCRIPTION

N·m

Ft. Lbs.

In. Lbs.

Tire Pressure Sensor/

Transmitter

Mounting Nut

6.5

—

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TIRES/WHEELS - SERVICE INFORMATION

SENSOR

DESCRIPTION

On vehicles equipped with Tire Pressure Monitoring
(TPM), one tire pressure sensor (6) is mounted to
each wheel (5) in place of the traditional tire valve
stem. 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 TPM system operates on a 315 MHz radio fre-
quency. The 315 MHz sensors can be easily identified
by a white outline oval (black center) insignia (3) on
the sensor body.

TIRES/WHEELS - SERVICE INFORMATION

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The Export TPM system operates on a 434 MHz radio
frequency. The 434 MHz sensors can be easily iden-
tified by a solid white oval insignia (3) on the body.

CAUTION: Although 315 MHz and 434 MHz sensors are identical in size and shape, they are not inter-
changeable. Always make sure the correct sensor is being used.

The TPM sensors are designed for original style factory wheels. Do not attempt to install a tire pressure sensor
in an aftermarket wheel.

The serviceable components of the tire pressure sen-
sor are :

•

Sensor-To-Wheel Seal (2) and Metal Washer (1)

•

Valve Stem Cap (4)

•

Valve Stem Core

•

Valve Stem Nut (with pressed-in washer) (3)

The valve stem caps and cores used are specifically designed for the tire pressure monitoring sensors. Although
similar to standard valve stem caps and cores, they are different. The valve stem cap has a special seal inside to
keep moisture and corrosion out. The valve stem core has a special nickel coating to protect from corrosion.

OPERATION

The battery operated tire pressure 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 approx-
imately 20 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 pres-
sure status at that time.

Using an RF signal, each sensor transmits tire pressure data approximately once every minute. Each sensor’s
(transmitter) broadcast is uniquely coded so that the wireless control module (WCM) can monitor the state of each

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TIRES/WHEELS - SERVICE INFORMATION

of the sensors on the four rotating road wheels. The WCM automatically learns and stores the sensor’s ID while
driving after a sensor has been replaced. There is no formal retraining procedure necessary.

For additional information, refer to appropriate diagnostic information.

CAUTION

CAUTION: The use of tire sealants is strictly prohibited for vehicles equipped with the Tire Pressure Mon-
itoring system. Tire sealants can clog tire pressure sensors.

CAUTION: Tire pressure sensor valve stem caps and cores are specially designed for the sensors. Due to
risk of corrosion, do not use a standard valve stem cap or core in a tire pressure sensor in place of the
original equipment style sensor cap and core.

CAUTION: Do not attempt to install a tire pressure sensor in an aftermarket wheel. Use tire pressure sen-
sors in original style factory wheels only.

CAUTION: Any time a sensor is to be installed in a wheel, a new seal and washer must be installed on the
stem to ensure air tight sealing.

NOTE: TPM thresholds have been established for the original tire size equipped on the vehicle. Use original
size tires only to maintain system accuracy.

DIAGNOSIS AND TESTING

TIRE PRESSURE SENSOR

NOTE: Tire pressure may increase from 2 to 6 psi (14 to 41 kPa) during normal driving conditions. Do NOT
reduce this normal pressure build up.

When diagnosing a tire pressure issue, always check air pressure in the tires first with a known accurate air gauge.
Adjust air pressure as necessary to that listed on the Tire Inflation Pressure Label (Placard) provided with the vehi-
cle (usually applied to the driver’s side B-pillar). After adjusting air pressure in a tire, allow approximately two min-
utes for the message or yellow telltale to go out.

Check the tire pressure yellow telltale in the instrument cluster. If the yellow telltale is illuminating continuously, pro-
ceed as listed below. If the yellow telltale is flashing on/off for 60 seconds, once every ten minutes, there is a sys-
tem fault detected. Refer to the appropriate diagnostic information.

If air pressure in any tire is low, inspect all the tires for leaks. A water “dunk tank” or other water test may be used
to check for a leak around the sensor as long as any water at the valve core is removed once the procedure is
completed. The water can be easily expelled from the core area by pushing in on the core for several seconds,
allowing escaping air to drive out any moisture. Reinflate the tire as necessary. Always make sure the original valve
stem cap is securely installed to keep moisture out of the sensor.

If the gauge-read pressure in the tires does not indicate a tire pressure issue, refer to the appropriate diagnostic
information.

REMOVAL

1. Raise and support vehicle. (Refer to LUBRICATION & MAINTENANCE/HOISTING - STANDARD PROCEDURE)

2. Remove the tire and wheel assembly. (Refer to 22 - TIRES/WHEELS - REMOVAL)

CAUTION: The cap used on this valve stem contains an O-ring seal to prevent contamination and moisture
from entering the valve stem. Retain this valve stem cap for reuse. Do not substitute a regular valve stem
cap in its place.

TIRES/WHEELS - SERVICE INFORMATION

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