Tire Monitoring System

DIAGNOSIS AND TESTING - TIRE PRESSURE MONITORING SYSTEM Description and Operation . 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 vehicle (usually applied to the driver's side B-pillar). After adjusting air pressure in a tire on the vehicle, allow approximately two minutes for the message or indicator lamp to go out. Check the tire pressure indicator lamp in the instrument cluster. If the lamp is illuminating continuously, proceed as listed below. If the indicator lamp is flashing on/off for 75 seconds and then remains on solid, a system fault was 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 leaks 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.

PREMIUM TIRE PRESSURE MONITORING The operation and lamp/chime strategy for a premium tire pressure monitoring system (TPMS) is the same as the base TPMS, but the premium TPMS can display text messages and a graphic display of the tire pressure on the information cluster. If a low pressure condition is detected, in addition to a chime and the indicator lamp turning ON, a low pressure text message indicating which tire is low will be displayed in the instrument cluster for 3 seconds. This text message will be followed by a graphic display of the pressure value(s) with the low tire(s) flashing. Once pressure in the suspect tire raises above the Low Pressure (lamp) OFF Threshold (see placard table below), the lamp will go out and the system returns to normal within approximately two minutes time. If a system fault is detected, in addition to the flashing lamp, a "Service Tire Press.System" text message will be displayed in the instrument cluster, and the graphic display will have "- -" in place of the pressure value. The system will return to normal once the WCM receives a valid transmission from that sensor location A Premium Tire Pressure Monitoring System (TPMS) determines the location of the tire pressure sensors by using transponders located in three of the four wheel wells on the vehicle. A fourth transponder is not necessary in the remaining wheel well due to the process of elimination theory. Once the system knows the location of the first three sensors, it assumes the location of the fourth tire pressure sensor, and update the graphic display when necessary. For more information, (Refer to TIRES/WHEELS/TIRE PRESSURE MONITORING/TRANSPONDER - OPERATION). For both the premium and base TPMS, 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, 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. TPM THRESHOLD PRESSURES

This system will consist of Tire Pressure Monitoring (TPM) sensors attached to each wheel through the valve stem mounting hole, a Wireless Control Module (WCM) and a yellow TPM telltale lamp. A TPM sensor shall be installed in the spare wheel if the vehicle is equipped with a matching full size spare wheel and tire

The system will consist of tire pressure monitoring sensors attached to each wheel through the valve stem mounting hole, a wireless control module (WCM), three wheel sensor transponders located in three of the four wheel wells (Left Front, Right Front, and Left Rear), a re-configurable dot matrix display module (EVIC), and a yellow telltale.

The Tire Pressure Monitoring (TPM) system monitors air pressure in the four road tires (excludes spare). Pressure in the spare tire is not monitored. The base system does not specify how many tires are low or where they are located. The premium system does so.

There are two types of TPM available for this vehicle, a base system and a premium system.

The Base TPM system consists of tire pressure monitoring sensors attached to each road wheel through the valve stem mounting hole, a central receiver module (WIN) and an indicator lamp.

The Premium TPM system consists of tire pressure monitoring sensors attached to each road wheel through the valve stem mounting hole, a wireless control module (WIN) three wheel sensor transponders located in three of the four wheel wells, an electronic display, and an indicator lamp.

The receiver circuit for the TPM system is integrated into the WIN for non remote start vehicles. for factory installed remote start vehicles the antenna is external. Commonly referred to as the Wireless Control Module (WCM), the WIN also includes the Ignition Node, the Remote Keyless Entry (RKE) receiver and the Sentry Key Immobilizer (SKIM) receiver. All receivers share a number of common components. The WIN decodes the RF signals transmitted by each of the vehicle's tire pressure sensors. The decoded information is used to determine if "warning" or "fault" conditions exist within the TPM system.

Upon detection of a warning or fault condition, the WIN will send a request to the module that controls the indicator lamp (and the text display if equipped with the Premium system) via the vehicle bus system to illuminate or flash the indicator lamp. Also, upon detection of a warning or fault condition, the electronic

display will send a request to sound the "chime". A chime will only be requested once per ignition cycle per warning or fault condition detected.

The WIN 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 will store all wheel sensor ID's and locations and faults in memory that can be accessed through diagnostic communication. All other data values transmitted from each active wheel sensor (not the spare tire) shall be stored in the WIN memory.

The WIN automatically learns and stores the sensors's ID while driving "within 10 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.

The tire pressure monitoring system (TPMS) is designed to operate without loss of function for all OEM tire construction for this vehicle. Tire Pressure Monitoring Sensors, mounted to each road wheel as part of the valve stem, transmit an RF signal indicating their individual pressure to a receiver located in the Wireless Control Module (WCM), commonly referred to as the Sentry Key Remote Entry Module (SKREEM). These transmissions occur approximately once every minute at speeds over 15 mph (24 km/h). Refer to SENSOR - TIRE PRESSURE . 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 under TPM THRESHOLD PRESSURES), 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 and then remains on solid.

If the WCM detects a warning or fault condition at ignition key "on" it will wait ten seconds +/- 10 % before sending the first request to illuminate the yellow telltale. 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 WCM 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 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, 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 under TPM THRESHOLD PRESSURES). The system will automatically update and the TPM warning lamp will extinguish once the updated tire pressures have been received.

The 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 WCM receives a valid transmission from that sensor location

The operation and lamp/chime strategy for a premium tire pressure monitoring system (TPMS) is the same as the base TPMS, but the premium TPMS can display text messages and a graphic display of the tire pressure on the information cluster. If a low pressure condition is detected, in addition to a chime and the indicator lamp turning ON, a low pressure text message indicating which tire is low will be displayed in the instrument cluster for 3 seconds. This text message will be followed by a graphic display of the pressure value(s) with the low tire (s) flashing. Once pressure in the suspect tire raises above the Low Pressure (lamp) OFF Threshold (see placard table under TPM THRESHOLD PRESSURES), the lamp will go out and the system returns to normal within

approximately two minutes time. If a system fault is detected, in addition to the flashing lamp, a "Service Tire Press.System" text message will be displayed in the instrument cluster, and the graphic display will have "- -" in place of the pressure value. The system will return to normal once the WCM receives a valid transmission from that sensor location

A Premium Tire Pressure Monitoring System (TPMS) determines the location of the tire pressure sensors by using transponders located in three of the four wheel wells on the vehicle. A fourth transponder is not necessary in the remaining wheel well due to the process of elimination theory. Once the system knows the location of the first three sensors, it assumes the location of the fourth tire pressure sensor, and update the graphic display when necessary. For more information, Refer to TRANSPONDER .

For both the premium and base TPMS, 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, 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.

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.

NOTE: 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 also decrease. Tire pressure should always be set based on cold inflation tire pressure. For details, see DESCRIPTION.

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 vehicle (usually applied to the driver's side B-pillar). After adjusting air pressure in a tire on the vehicle, allow approximately two minutes for the message or indicator lamp to go out.

Check the tire pressure indicator lamp in the instrument cluster. If the lamp is illuminating continuously, proceed as listed below. If the indicator lamp is flashing on/off for 75 seconds and then remains on solid, a system fault was 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 leaks 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.