Tire Pressure Sensor: Description and Operation
SENSORDESCRIPTION
NOTE: On vehicles equipped with a Tire Pressure Monitoring System (TPMS), when the spare tire pressure sensor is replaced with a new pressure sensor, a diagnostic scan tool MUST be used to run a routine that will program the new pressure sensor ID into the Wireless Control Module (WCM), commonly referred to as the Sentry Key Remote Entry Module (SKREEM). Please copy the ID number off of the new pressure sensor before installing it into the spare tire. Then follow the programming steps outlined in the diagnostic scan tool for: "Learn Spare Tire Sensor ID" under" Miscellaneous Functions" for the "WCM/Wireless Control Module" menu item as appropriate.
NOTE: If replacing the WCM, the spare tire must be dismounted from its wheel to access and note the spare tire pressure sensor ID. Then follow the programming steps outlined in the diagnostic scan tool for "Learn Spare Tire Sensor ID" under "Miscellaneous Functions" for the "WCM/Wireless Control Module"? menu item as appropriate. In addition, the placard pressure thresholds must be updated in the new WCM. Go to "Update Pressure Thresholds" under "Miscellaneous Functions" for the "WCM Wireless Control Module" and follow the procedure.
On vehicles equipped with Tire Pressure Monitoring System, 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 frequency. The 315 MHz sensors can be easily identified by a white outline oval (black center) insignia (3) on the sensor body.
The Export TPM system operates on a 433 MHz radio frequency. The 433 MHz sensors can be easily identified by a solid white oval insignia (3) on the body.
CAUTION: Although 315 MHz and 433 MHz sensors are identical in size and shape, they are not interchangeable. 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 sensor 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 approximately 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 pressure status at that time.
Using an RF signal, each sensor transmits tire pressure data approximately once every minute only in drive mode. Each sensor's (transmitter) 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 automatically learns and stores the sensor's ID while driving after a sensor has been replaced.
NOTE: On vehicles equipped with a Tire Pressure Monitoring System (TPMS), when the spare tire pressure sensor is replaced with a new pressure sensor, a diagnostic scan tool MUST be used to run a routine that will program the new pressure sensor ID into the Wireless Control Module (WCM), commonly referred to as the Sentry Key Remote Entry Module (SKREEM). Please copy the ID number off of the new pressure sensor before installing it into the spare tire. Then follow the programming steps outlined in the diagnostic scan tool for: "Learn Spare Tire Sensor ID" under" Miscellaneous Functions" for the "WCM/Wireless Control Module" menu item as appropriate.
NOTE: If replacing the WCM, the spare tire must be dismounted from its wheel to access and note the spare tire pressure sensor ID. Then follow the programming steps outlined in the diagnostic scan tool for "Learn Spare Tire Sensor ID" under "Miscellaneous Functions" for the "WCM/Wireless Control Module"? menu item as appropriate. In addition, the placard pressure thresholds must be updated in the new WCM. Go to "Update Pressure Thresholds" under "Miscellaneous Functions" for the "WCM Wireless Control Module" and follow the procedure.
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 Monitoring 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 sensors 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.