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