Last Warning Event PID Definitions
The TPMS uses the TPMS last warning event Parameter Identifications (PIDs) to store detailed information about the last 5 times the TPMS warning indicator was activated. These Parameter Identifications (PIDs) can be used to acquire more information about a particular TPMS event, but must be used carefully.
Definition | |||
|---|---|---|---|
PID | |||
EVT1_AGE_IGN through EVT5_AGE_IGN | The number of key cycles since the TPMS was activated. This PID cycles from zero to 255 and then starts over from zero again. This can be used to determine how long ago a TPMS event occurred and the time (in key cycles) between events. | ||
EVT1_TR_LOC through EVT5_TR_LOC | This is the last programmed location for the TPMS sensor identifier causing each TPMS event. Due to tire rotation, the sensor may no longer be at the original location. It is suggested that all the Parameter Identifications (PIDs) be recorded, the system retrained, and then the sensor identifier Parameter Identifications (PIDs) be used to pinpoint the actual location of each sensor. | ||
EVT1_PRES_BP through EVT5_PRES_BP | This is the tire pressure associated with each TPMS indicator event. This can be used along with the function code to clearly identify the TPMS events that were strictly due to low pressure. It can also be used to determine when a sensor is transmitting inaccurate tire pressure. | ||
EVT1_SNSR_ST through EVT5_SNSR_ST | Describes the warning status of each TPMS event by using the information received from the TPMS_STATUS PID. If there is a communication concern, the status could be NORMAL. UNKNOWN NORMAL (normal operation) LOW (low pressure event) FAULT (sensor fault or system fault) | ||
EVT1_SNSR_ID through EVT5_SNSR_ID | This is the identifier of the sensor involved in each TPMS event. EVT1 is the most recent event that triggered the TPMS warning indicator. | ||
Radio Frequency Interference (RFI)
RFI can be caused by:
Video equipment has been found to cause RFI especially when the video and power supply lines are near the TPMS. Anti-theft alarms (even those installed by the dealership) have been found to create enough RFI to cause the TPMS to malfunction or lose considerable range. These anti-theft alarms can be difficult to locate, as they are usually hidden somewhere out of the way for reduced accessibility. Many in-vehicle cell phone chargers have been found to cause considerable RFI. The vehicles with the power point closest to the RTM are the most affected. It must be noted that most cell phone chargers do not produce high levels of RFI all the time. This depends on the state of charge of the cell phone battery. The phone battery must be almost completely discharged in some cases. Power supplies and DC/ AC inverters typically create a lot of RFI. Most consumer grade equipment has
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