Wrangler 2WD V6-3.8L (2008)
Tire Pressure Sensor: Description and Operation
Operation
OPERATION
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.If a TPM-RKE Analyzer special
tool is available, put the new spare tire pressure sensor into "Park" mode to conserve the battery life of the sensor. If a TPM-RKE Analyzer
special tool is not available, rotate the spare tire with one of the road tires
NOTE: If replacing the WCM, the spare tire must be dismounted from its wheel to access and note the spare tire pressure sensor ID.
Alternatively, a TPM-RKE Analyzer Tool can be used to obtain the TPM sensor ID also. 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.
The battery operated tire pressure sensor is both a transmitter and a receiver. The TPM sensor can be forced to transmit if using a special tool such as a
TPM-RKE Analyzer, or from a transponder. The TPM-RKE Analyzer has the ability to change the sensor's operating mode and to diagnose a faulty
TPM sensor. Using a TPM-RKE Analyzer can take up to a minute to force a transmission from a sensor. The TPM sensor can be in one of the following
modes:
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Sleep Mode - This is the operating mode of a new TPM sensor. If placed on the vehicle as a road tire, the sensor will transmit once every 20
seconds when the vehicle is driven at speeds over 15 mph (24 km/h). If the vehicle is not moving, the sensor will only transmit on a pressure
change greater then 1 PSI. Driving the vehicle continuously at this speed for more then 4 minutes will change the sensor state into 30 BLOCK
MODE. The TPM sensor will not return to SLEEP MODE. Now, if the vehicle has been stopped for 20 minutes, the TPM sensor state will change
to PARK MODE. If the vehicle is equipped with a full size matching spare tire and the spare tire sensor has been replaced, The sensor must be
changed to Park Mode to conserve battery life. Either use a TPM-RKE Analyzer, or swap the spare tire with a road tire.
-
Park Mode - This is the correct operating mode when the vehicle is not moving. The sensor will transmit once every 13 hours to update the
WCM, or will transmit on a 1 PSI delta change. The sensors will internally take a measurement of the tire pressure every minute to determine a
change in tire pressure
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30 Block Mode - If the vehicle has been stopped for more then 20 minutes, or if the sensor's operating mode was forced to Park Mode using a
TPM-RKE Analyzer, the sensor's operating mode will transition from Park Mode to 30 Block Mode once the vehicle is driven over 15mph. In this
mode, the sensor will transmit once every 15 seconds when the vehicle is driven at speeds over 15 mph (24 km/h) for the first 30 transmissions.
After about 8 minutes of continuous driving above 15 mph (24 km/h), the sensor's mode will change to Drive Mode
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Drive Mode - In this mode, the sensor will transmit once every minute when the vehicle is driven at speeds over 15 mph (24 km/h). At any time
the vehicle speed drops below 15 mph, the sensor will not transmit. The sensor mode will still be in drive mode when the sensor reaches speeds
over 15 mph (24 km/h), If the vehicle has been stationary for more then 20 minutes, the TPM sensor will change to PARK 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 can automatically learn and store the sensor's ID while driving "within 10 minutes continuously above 15 m.p.h.
(24 Km/h)" after a sensor has been replaced, The vehicle must be stationary for more then 20 minutes in order to initiate the learning sequence. The
sensor IDs can also be programmed using the TPM-RKE Analyzer Tool. Scan each TPM sensor at each road wheel, and store each Sensor ID in the
correct location. (LEFT FRONT, LEFT REAR, RIGHT FRONT, and RIGHT REAR) Connect the TPM-RKE Analyzer Tool to the Scan Tool. Then
follow the programming steps outlined in the diagnostic Scan Tool for "Program Tire Pressure Sensor ID w/ TPM Tool" under "MISC" for the
"WCM/WIRELESS CONTROL MODULE".
