Chrysler 2005 Crossfire SRT6 Service Manual page 3537

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CAUTION: Do not attempt to install a tire pressure sensor in a steel wheel or aftermarket wheel. Use tire
pressure sensors in original style factory wheels only.
A tire pressure sensor/transmitter is installed in each wheel of this vehicle as part of the tire pressure monitoring
system. A special valve stem incorporated into each tire pressure sensor/transmitter attaches it to the wheel.
VALVE STEM CORE AND CAP
On this vehicle, the valve stem is part of the tire pressure sensor/transmitter and is used as its antenna. If corrosion
were to develop in the valve stem, it would affect the ability of the tire pressure sensor/transmitter to send the radio
frequency signal to the TPM module.
The valve stem used on this vehicle is made from aluminum. Corrosion of aluminum will be caused by putting a
dissimilar metal in contact with it. To prevent this type of corrosion from developing within the valve stem, the core
of the valve stem is made of a compatible metal and is specially coated.
For this reason, a standard valve stem core must never be installed in this valve stem. If the core of the valve stem
is removed when servicing the tire, the original valve stem core must be reinstalled. If the valve stem core needs to
be replaced, it must be replaced with an original equipment valve stem core.
The valve stem caps used on this vehicle are specially designed for their use on the valve stem of the tire pressure
sensor/transmitter. Each valve stem cap has an O-ring in the upper end of the valve stem cap to provide a positive
seal at the end of the valve stem. This keeps dirt, contamination and corrosion out of the valve stem caused by
moisture. As listed earlier, these conditions can affect the ability of the tire pressure transmitter to send the radio
frequency signal to the TPM module.
OPERATION
Each Tire Pressure Sensor/Transmitter serves three functions:
• It is used as a valve stem to inflate and deflate the tire.
• It periodically measures tire pressure. (Approximately every 30 seconds.)
• It transmits the tire pressure value to the Tire Pressure Monitor (TPM) module in the vehicle. (Approximately
every 60 seconds or if tire pressure changes by one psi or more between transmissions.)
The system operates by monitoring a radio frequency transmission from the sensor/transmitters located in each
wheel. When the vehicle reaches a speed of approximately 32 km/h (20 MPH), centrifugal force created by the
rotating wheels closes a roll switch inside each sensor/transmitter, powering up the circuitry.
The sensor/transmitters will only send out information when vehicle speed is above 32 km/h (20 MPH). To facilitate
transmitting the radio signal to the TPM module, the valve stem acts as the antenna for the tire pressure sensor/
transmitter. When the TPM module senses that pressure is below one of two calibrated thresholds, (low pressure or
critical pressure) the TPM system will set a diagnostic trouble code and indirectly operate the "Low Tire" pressure
indicator lamp and the chime tone through the Body Control Module (BCM).
The tire pressure sensor/transmitter is powered by an internal battery. The battery is not replaceable separately. In
the event of battery failure, the entire tire pressure sensor/transmitter at that wheel will require replacement. To
extend the life of the battery, the sensor/transmitter is not activated until the vehicle reaches a speed of approxi-
mately 32 km/h (20 MPH) as stated earlier.
Each tire pressure sensor/transmitter has a unique identity code. This will allow the TPM system to indicate to a
technician, through Diagnostic Trouble Codes (DTCs) in the module, which tire of the vehicle has lost air pressure.
This code is also used to identify to a technician which pressure sensor/transmitter has set a DTC. For this reason,
if a tire pressure sensor/transmitter needs to be replaced, the new sensor/transmitter must be programmed to have
its identity code recognized by the receiver.
REMOVAL
CAUTION: When removing the stick-on balancing weights from the wheel, do not use an abrasive cleaner or
a cleaner which will damage the protective finish on the wheel.
Note: 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 22 - 51