TPMS Function

NOTE: When directed to train any TPMS sensors, use only the sensor training procedure outlined in this article. Do not use the TPMS reset procedure outlined in the Owner's Literature as this procedure does not program new sensors to the module.

The TPMS uses 4 valve stem mounted sensors to monitor tire pressure. These sensors transmit tire pressure data to the Radio Frequency (RF) receiver. Each TPMS sensor contains a battery and transmits tire pressure data to the Radio Frequency (RF) receiver using Radio Frequency (RF) transmission. The Radio Frequency (RF) receiver is a radio receiver that collects the tire pressure data and sends the information to the BCM along a LIN. All TPMS functions are controlled by the BCM. The TPMS sensors are trained (calibrated) to the BCM, which records the unique identifier for each sensor. The BCM records the location of each TPMS sensor based on the training order and compares the tire pressure data sent by the sensors with a programmed tire pressure. This programmed pressure is specified on the VC label. If the actual tire pressure deviates from the programmed tire pressure the BCM, using the MS-CAN, signals the IPC to illuminate the TPMS warning indicator and display a message in the message center. The programmed tire pressure cannot be changed.

The diagnostic scan tool is useful in diagnosing TPMS concerns and may be used to verify the accuracy of the tire pressure data transmitted by the TPMS sensors. This is accomplished by comparing the BCM tire pressure PID data to the actual tire pressure using a digital tire pressure gauge.

Following a tire rotation on vehicles with different front and rear tire pressures, the tire pressures must be adjusted and the TPMS sensors must be trained (calibrated). Refer to: Tire Pressure Monitoring System (TPMS) Sensor Location Calibration .

Wheel Rotation and Sensor Training Techniques

Training known good sensors from another vehicle can help determine whether the concern is with a sensor or the Radio Frequency (RF) receiver. This technique cannot help determine whether the concern is due to Radio Frequency Interference (RFI) as some Radio Frequency Interference (RFI) source could be preventing the Radio Frequency (RF) receiver from receiving the tire pressure status from the known good sensors as well as the original sensors.

If the Radio Frequency (RF) receiver in the suspect vehicle cannot train any of the original sensors and also cannot train known good sensors from another vehicle, then the concern is with the module or Radio Frequency Interference (RFI) and not with the original sensors. The original sensors should not be replaced. If a sensor in a certain location has caused several events, yet the sensor trains and seems to operate normally, moving that particular wheel to a different location on the vehicle is a good way to isolate the concern to a certain sensor or wheel location. Rotate the wheels and road test the vehicle. This can be done in an attempt to replicate the concern and help determine if the concern followed the sensor or remained in the original sensor location.

If the vehicle has been stationary for more than 30 minutes, the sensors enter into a "sleep mode" to conserve battery power and need to be "woken up" so they transmit the latest tire pressure information to the Radio Frequency (RF) receiver. Refer to: Tire Pressure Monitoring System (TPMS) Sensor Activation .

Training Sensors in a Different Order

If the first sensor fails the TPMS training procedure, the BCM aborts the entire procedure. Starting the training procedure at a different wheel is a technique used to determine if the remaining sensors can train to the module. This can help save time determining if one sensor is damaged, other sensors are having concerns or the BCM is experiencing training difficulties with a certain TPMS sensor location.