Tire Pressure Monitoring (TPM) - Operation
OPERATION
The Tire Pressure Monitoring (TPM) system monitors air pressure in the four road tires, or if the vehicle original equipment includes a full size matching spare, then all five tires. Pressure in the spare tire is not monitored with a compact spare or a "non-matching spare.
There are two tire pressure monitoring systems available, a base system and a premium system. The base system does not specify how many tires are low or where they are located. The premium system does indicate which tire is low.
LIGHT LOAD SWITCH
On the 2500 series base and premium systems there is a "Light Load" switch located on the instrument panel in the center stack. If equipped, these vehicles will have two different recommended tire pressure values depending on the vehicle load/switch setting. The Light Load switch which will allow the driver to change between two different recommended "Placard Pressure", "Low-pressure Threshold" and Hysteresis Pressure Values". These values are stored in the modules non-volatile memory during the initial Manufacturing Plant Process, or during a service procedure, as required. To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label or Supplemental Tire Pressure Information Label, and then apply the placard pressure to the following table. The Low Pressure OFF Threshold is defined as the Low Pressure ON Threshold plus the Hysteresis Pressure Value.
BASE TIRE PRESSURE MONITORING
The tire pressure monitoring (TPM) system is designed to operate without loss of function for all OEM tire construction for this vehicle. Sensors, mounted to each road wheel (and spare if equipped with a sensor) as part of the valve stem, transmit an RF signal indicating their individual pressure to the Tire Pressure Monitoring (TPM) module for the 2500 series, or the Wireless Ignition Node (WIN) for the 1500 series. These transmissions occur approximately once every minute at speeds over 15 mph (24 km/h). For more information on sensors, Tire Pressure Monitoring (TPM) Sensor - Operation.
If the TPM system detects that the tire pressure in any road tire is going low, beyond the Low Pressure (lamp) ON threshold (see placard table below), the TPM system will continuously illuminate an indicator lamp. If a system fault is detected, the indicator lamp will flash on/off for 75 seconds, then remain on solid.
If the WIN or TPM module detects a warning or fault condition at ignition key "ON" it will wait ten seconds +/- 10 % before sending the first request to illuminate the indicator lamp. 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" or "fault" condition detected. A "warning" or "fault" condition will remain enabled until the problem causing the condition is corrected and removed/reset.
The WIN or TPM module will store all warning and fault conditions, placard pressure values and low-pressure threshold values (lamp ON and OFF) in memory that can be accessed through diagnostic communication. If new sensors are introduced to the vehicle, the data stored for the sensor being replaced will be deleted.
The WIN or TPM module will store all wheel sensor ID's and locations and faults in memory that can be accessed through diagnostic communication, and all other data values transmitted from each active wheel sensor.
The WIN or TPM module shall continuously monitor for the receipt of tire pressure RF message transmissions from the wheel sensors during both the ignition key "ON" and key "OFF" cycles. The wheel sensor ID's and the location of each sensor (e.g. Tire 1, Tire 2 etc.) are learned by the WIN or TPM during the initial Manufacturing Plant Process, or during a service procedure, as required.
The TPM System will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off the indicator lamp until the tire pressure is at or above the Low Pressure (lamp) OFF threshold (see placard table below). The system will automatically update and the TPM indicator lamp will extinguish once the updated tire pressures have been received.
NOTE: A new sensor ID can also be programmed directly into the WIN or TPM module by using a RKE-TPM Analyzer in conjunction with a Scan Tool. Once the new sensor ID has been programmed, the vehicle will need to be driven above 15 mph until the fault is no longer active (lamp extinguishes) and display is updated (for up to 20 minutes).
The WIN or TPM automatically learns and stores the sensor IDs while driving "within 20 minutes continuously above 15 mph (24 km/h)" after a sensor has been replaced. The learning sequence will initiate when the vehicle has been stopped for more than 20 minutes.
Tire pressure will vary with temperature by about 1 psi (6.9 kPa) for every 12°F (6.5°C). This means that when the outside temperature decreases, the tire pressure will decrease. Tire pressure should always be set based on cold inflation tire pressure (placard pressure). This is defined as the tire pressure after a vehicle has not been driven for more than 3 hours (and in outside ambient temperature). The tire pressure will also increase as the vehicle is driven; this is normal and there should be no adjustment for this increased pressure. For a system fault, the system will return to normal once the WIN receives a valid transmission from that sensor location.
The recommended "Placard Pressure", "Low-pressure Threshold" (Low Pressure ON) and "Hysteresis Pressure" values for the tires installed on the vehicle, are learned by the WIN module configuration during the initial Manufacturing Plant Process, or during a service procedure, as required.
To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label, and then apply the placard pressure to the following table. The Low Pressure OFF Threshold is defined as the Low Pressure ON Threshold plus the Hysteresis Pressure value.
For further information, refer to the Owners Manual or the Appropriate Diagnostic Information.
PREMIUM TIRE PRESSURE MONITORING
The Tire Pressure Monitoring (TPM) system is designed to operate without loss of function for all OEM tire construction for this vehicle. Sensors, mounted to each road wheel (and spare if equipped with a sensor) as part of the valve stem, transmit an RF signal indicating their individual pressure to a receiver located in the Tire Pressure Monitoring (TPM) module. These transmissions occur approximately once every minute at speeds over 15 mph (24 km/h). For more information on sensors, Tire Pressure Monitoring (TPM) Sensor - Operation.
If the TPM module detects that the tire pressure in any road tire is going low, beyond the Low Pressure (lamp) ON threshold (see placard table below), a chime will sound and the indicator lamp will turn on. In addition to the chime and lamp, a graphic display of the pressure value(s) and position of the low tire(s) will flash in the Electronic Vehicle Information Center (EVIC). Once pressure in the suspect tire(s) raises above the Low Pressure (lamp) OFF Threshold (see placard table below), and the TPM module receives a valid transmission from the sensor the lamp will go out. If a system fault is detected due to a missing sensor signal, in addition to a chime and a indicator lamp flashing, a "Check TPM System" text message will be displayed in the instrument cluster, and the tire pressure graphic display will display "- -" in place of the pressure value. After the flash sequence the TPM indicator lamp will remain illuminated. The system will return to normal once the TPM module receives a valid transmission from that sensor location. If a system fault is detected, the indicator lamp will flash on/off for 75 seconds and then remain on solid.
If the TPM module detects a warning or fault condition at ignition key "ON" it will wait approximately ten seconds before sending the first request to illuminate the indicator lamp. This will assure that the display module has concluded its bulb check period. The display module will request a chime once per ignition cycle when a "warning" or "fault" condition is detected. A "warning" or "fault" condition will remain enabled until the problem causing the condition is corrected and reset.
NOTE: A new sensor ID can also be programmed directly into the WIN or TPM module by using a RKE-TPM Analyzer in conjunction with a Scan Tool. Once the new sensor ID has been programmed, the vehicle will need to be driven above 15 mph until the fault is no longer active (lamp extinguishes) and display is updated (for up to 20 minutes).
The TPM module shall continuously monitor for the receipt of tire pressure RF message transmissions from the wheel sensors during the ignition key "ON" cycle. The wheel sensor ID's and the location of each sensor (e.g. Tire 1, Tire 2 etc.) are learned by the TPM control module using signal strength and direction of wheel rotation as received by the TPM module from each of the sensors, and updates the graphic display when necessary or during a service procedure, as required.
The TPM System will continue to warn the driver of low tire pressure as long as the condition exists, and will not turn off the indicator lamp until the tire pressure is at or above the Low Pressure (lamp) OFF threshold (see placard table below). The system will automatically update and the TPM indicator lamp will turn off once the updated tire pressures have been received.
Tire pressure will vary with temperature by about 1 psi (6.9 kPa) for every 12°F (6.5°C). This means that when the outside temperature decreases, the tire pressure will decrease. Tire pressure should always be set based on cold inflation tire pressure (placard pressure). This is defined as the tire pressure after a vehicle has not been driven for more than 3 hours (and in outside ambient temperature). The tire pressure will also increase as the vehicle is driven? this is normal and there should be no adjustment for this increased pressure. For a system fault, the system will return to normal once the TPM module receives a valid transmission from that sensor location.
The recommended "Placard Pressure", "Low-pressure Threshold" (Low Pressure ON) and "Hysteresis Pressure" values for the tires installed on the vehicle, are learned by the TPM module configuration during the initial Manufacturing Plant Process, or during a service procedure, as required.
To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label, and then apply the placard pressure to the following table. The Low Pressure OFF Threshold is defined as the Low Pressure ON Threshold plus the Hysteresis Pressure value.
For further information, refer to the Owners Manual or the Appropriate Diagnostic Information.
TPM THRESHOLD PRESSURES
NOTE: To determine the pressure thresholds for a vehicle, refer to the Tire Inflation Pressure (Placard) Label found on the Driver's B-Pillar, then apply the placard pressure to the following table.
