TPMS another question

[Bedrck47]

the following was copied from the service manuals

for the 2003 model year
Principles of Operation

The tire pressure monitoring system (TPMS) has the ability to monitor the air pressure of all five tires. The tire-mounted pressure sensors transmit signals to the TPMS module by using the valve stem as an antenna. These transmissions are sent approximately every 60 seconds when the vehicle speed exceeds 32 km/h (20 mph). The TPMS module compares each tire pressure sensor transmission against low and high pressure limits. If the TPMS module determines that the tire pressure has exceeded the limit, the TPMS module communicates on the SCP network to the vehicle message center, which then displays a warning message. The system is not affected by wheel and tire rotation.

for the 2004 thru 2010 model years
Principles of Operation

The tire pressure monitoring system (TPMS) monitors the air pressure of all four regular road tires. The tire-mounted pressure sensors transmit via radio frequency (RF) signals to the TPMS module, using the valve stem as an antenna. These transmissions are sent approximately every 60 seconds when the vehicle speed exceeds 32 km/h (20 mph). The TPMS module compares each tire pressure sensor transmission against a set of low-pressure limits. If the TPMS module determines that the tire pressure has fallen below these limits, the TPMS module communicates this on the SCP network to the vehicle's instrument cluster message center (if equipped), which then displays a warning message and the appropriate message center message. Vehicles without a message center have a continuously illuminated TPMS indicator in the instrument cluster.

 

[ExpeditionAndy]

Okay Roxy, so based on that, It will only complain when the tire pressure falls below a preset low. Other than that, it doesn't know if one tire is 4 lbs higher than the others?

The TPMS in my '09 Mercedes ML350, also monitored pressure differential between tires.

 

[Bedrck47]

imagine what ford would charge for a system like that lol

 

[Bedrck47]

this is something that causes me to get a little attitude and ask what year a person has.
The 03 did both high and low pressure warnings.
But after that it only does low pressure warnings.

At least according to the service manuals

 

[ExpeditionAndy]

I know what you mean.

It's probably a $.50 chip and a little programming. I wonder if they do it in the new models.

 

[khpony]

Thanks everyone. I had new tires mounted today and after buying the cd shop manual I just ordered the magnet to reset them. This should resolve my tpms issue. Thanks to everyone for their great advice. Now I'll be on to my next issue in another thread later.

 

[khpony]

Bought the magnet (actually 2 of them, don't ask) tried to set the system to no avail. I also have 4 new monitors in the box so I set them on top of each of the tires and tried that to no avail. Does this indicate that I need to have Ford reset the system? I've got to have them reset the drivers seat module for the heated/cooled seats so I'll be at the dealership anyways.

 

[ExpeditionAndy]

I think that your sensors have to be mounted in the wheels for it to work. (I'm thinking they have to see pressure.) Also make sure that you have the right sensors for your vehicle. There are different kinds and they are not all compatible. I think it has something to do with they frequency in which the transmit.

 

[khpony]

I bought the sensors off ebay and they were advertised as the correct freq for my Expo. recall reading another post where someone had put their new sensors on top of the tires and the system read them as low pressure. That's why I tried it but it didn't work for me. We have a 800mi trip comming up wthin the next month for the birth of a new grandson so I think I'll get it to the dealership and get it squared away. Don't need any problems while on a trip.
Thanks Andy!