On the 04-05 we only get an overall status like Durk says, ours don't know the actual PSI, only knows changes (and only alerts at a 12PSI change from reset). On the 07-08 it shows all 4 tires at actual PSI in pretty much real-time.
ALSO the DIC shows the mileage, but the PCM will still have the correct mileage stored. He's only breaking the law if he tries to sell or title the car with the wrong mileage listed.
$160 for the four sensors will fix your problem.
So far there isn't a solution to the problem other then to get the sensors.
If you choose to keep the 07 dic in addition to the four wheel sensors you will need a 07 keyless entry reciever as well.
This part changed in 07 because it has to be capable to receieve signals from the pressure sensors, The connectors are different just enough that they wont plug in so you will have to splice a connector or make an adapter harness and make a slight wiring modification so the keyless entry reciever has a direct link to the serial bus of the car.
The keyless entry reciever sends the tire pressure data over the serial bus where the dic picks it up and displays it.
The keyless entry reciever will have to me reprogramed for your new remotes, as well as learning the tire sensors.
What would happen if the TPMS module were removed?
In theory, The dic would think that there wasn't a TPMS to begin with and may not bother with throwingthe code anymore. You may have to reset the battery by removing the terminals for half an hour or so.
If it still comes up after that, try going to a dealer and explaining that you want them to disable your TPMS completely using a tech 2 and if they are a good dealer, they will do it for no more than a 1 hour rate, still leaving you up $100 from what buying 4 sensors would be.