Can anyone explain how the spare communicates with the BCM?

 

The tire has a radio frequency transmitter as part of the valve stem that transmits a signal a short distance to the BCM. Each unit has to be programmed into the TPMS so when there is a low pressure problem it can tell which tire has it.

 

Thanks!! My dealer says they didn't even know my vehicle had one in the spare and overlooked when installing new stems in four tires. Can programming of the TPMS be done by a tire shop or do I need to go back to Ford dealer?
Happy Friday!!!

 

There are a few ways to program the transmitters most of which require a TPMS tool.
Some spares don't contain a transmitter and therefore the system is not programmed to monitor them. They all contain a small internal battery that lasts anywhere from 7-10 years. If the vehicle is not moving within a specified time the transmitter turns off thereby conserving battery life. This can get a little complicated when different manufacturers use different means to monitor the system and some use wheel speed sensors(ABS) to monitor pressure change due to circumference differences.
Most tire shops have the necessary tools to program most sensors.

 

My main question has to do with the spare tire because it has a transmitter. Should it be communicating with my system? Dealer is claiming they didn't know the spare had one when they replaced the transmitters in the four main tires. Ford's documentation doesn't say anything about spares in the TPMS section of my manual.