How to Analyze the Actual TPMS Light Alarm?

Now there is an example, a Toyota car produced in 2010, when the driving range is about 3000 km, the phenomenon of TPMS fault light alarm on the dashboard has appeared. Every time a malfunction occurs, the owner will check the air pressure of each tire. Whenever the tire pressure is stored, the warning light will go out. However, the vehicle will report to the police after driving for a period of time, and the pressure monitoring system will alarm frequently. How to detect specific faults?

 

The specific detection and analysis methods are as follows:

 

1. First, connect the fault diagnosis instrument to test the vehicle and check whether the fault code meaning "tire diameter signal is unreliable/occasional" is stored in the tire pressure system control unit.

 

2. After this, conduct routine inspections to check whether the appearance, size and inflation pressure of the tire are normal, whether the tire has been replaced, and whether the wear of each tire pattern is evenly distributed.

 

3. Finally, the road test was used to check the alarm response of the tire pressure monitoring system when the vehicle was running after storing the tire pressure. If the alarm is repeated, observe the data flow of the TPMS system. If the alarm status of each tire at the time of the alarm is equal, it means that there is no abnormality in the wheel speed signal. At this time, you can try to replace the control unit and tires of the tire pressure monitoring system to find the specific source of the fault.

 

4. In addition, it can be analyzed by combining the basic technical principles of the vehicle model. The 2010 Toyota sedan uses an indirect measurement tire pressure monitoring system, and no tire pressure sensor is installed in the wheel. The TPMS receives the speed signals of the four wheel speed sensors sent by the control unit through the system bus, and analyzes to determine whether the tire is out of pressure.

 

In order to identify the air pressure loss on multiple tires, the TPMS system performs simultaneous analysis according to two different monitoring and analysis methods.

 

The first way: monitor the tire volume. When the tire pressure decreases, the tire volume will also become smaller. In this case, the wheels that travel the same distance must turn faster than the wheels without pressure loss. In the TPMS system, the rotational speeds of the diagonal wheels are added, and then compared, and then the speed signals of the coaxial wheels and the one-sided wheels are compared, and the wheels are analyzed in consideration of the driving factors such as cornering, centrifugal acceleration and steering angle, using speed signal to monitor tire status.

 

The second way: monitor tire vibration. Since the driving road is uneven, each tire will cause rolling vibration when rolling, and TPMS will analyze the vibration of the wheel by measuring the speed of each wheel. If the air pressure decreases, the vibration mode will change, and this analysis method can also measure the pressure loss of multiple tires.