Tire Pressure Monitor (TPM) System

Whenever the engine is running, the TPMS control unit continuously monitors all 4 tires and the system. If it detects less than 24 psi (168 kPa) in a tire, it alerts the driver by turning on the low pressure indicator, turning on the appropriate tire(s) indicator on the multi-information display, and setting a Diagnostic Trouble Code (DTC) in the control unit. When the tire pressure is increased to more than 29 psi (198 kPa), the control unit will turn off the indicators and store the DTC(s). When 2 or more tire pressures are low, the low pressure indicator comes on about 5 seconds before the appropriate tire indicator. Once low pressure is detected, the system scans all 4 pressure sensors to ensure that it turns on the correct tire indicator.

If a problem is detected in the system, the TPMS indicator will come on. If low tire pressure and a problem in the system are detected, only the TPMS indicator comes on. When the system detects a problem, the TPMS control unit sets a code, but shifts to fail-safe mode, and does not alert the driver to low tire pressures. If the TPMS control unit loses power or fails, the TPMS indicator will come on, but no DTC will be set.

Each sensor is an integrated unit made up of the tire valve stem, a pressure sensor, and a transmitter. The unit is attached to the inside of the wheel, around the valve stem. Each low pressure sensor has its own ID to prevent jamming by similar systems on other vehicles. After memorizing all the sensor IDs, the control unit receives only those specific signals. An ID can be memorized manually or automatically.

An initiator for each wheel (located in wheelhousing) is hardwired to the control unit. Every time the ignition is turned ON (II), the control unit asks each initiator for a sensor ID. The initiators then transmit the sensor IDs, and the control unit receives and memorizes them. The control unit then knows which ID belongs to each tire location. This recurring ID confirmation prevents any confusion in the system as a result of normal tire rotation.