The LTI (low tire indicator) was devised to help prevent accidents or roadside breakdowns due to low tire pressure. A receiver picks up the signal from the tire transponders located in each tire including the spare tire and then sends the information across an information bus to the LTI processor. These processors then compute information and send a signal to an on board diagnostic center which includes a warning light located on the dash. Some vehicles include integrated apps which can send a message to your phone when the low tire inductor warning system has been activated.
As you know a tire is like a balloon which can lose air from time to time, as part of regular vehicle maintenance you are expected to check the tire pressure using a tire pressure gauge. If the air pressure in all tires is correct including the spare and the indicator is still on, a tire pressure sensor has probably failed, or the system requires a reset procedure which can be done using a CAN scanner. Also, when replacing a worn tire with a new one the air pressure sensor can be damaged which then will require replacement, this is a common problem.
Pressure sensors are used to monitor individual tire pressure in all tires including
the spare. If air pressure in any given tire goes below or above minimum or maximum
requirements the warning light will illuminate. The image below shows how the LTI
system is configured which includes a sensor in each tire, the control unit, pressure
receiver which includes an antenna and a LTI warning light located in the dash cluster.
Nine times out of ten when the system has a problem it will be a tire pressure
sensor, which requires the tire to be removed from the rim and the sensor replaced.
If the warning system warns that all the tires are low chances are the main controller
or receiver needs to be replaced. Again, that can be checked by
performing a CAN scan.
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