I have a service tire system soon alert on my 2004

This is likely a mileage triggered warning. If you have good tires already, a rented scanner will allow you to reset the mileage goal and clear the message. Alternatively, go back to where you bought the tires and see if they will erase the warning.

You have a bad TPMS (Tire Pressure Monitor Sensor) that is not reading or is having failure problems. Maybe due to excessive pressure loss or the sensor is bad. They require maintenance just as anything else. Sears I know has TPMS kits that replace maintenance parts such as the rubber grommet seal, Lock ring, Special replacement valve core which is made of a different metal than whats is used on NON-TPMS systems, and lastly the TPMS cap. IF the tires were replace then they have to either sell you the maintenance kit or use the same TPMS parts. They would only have to remove the valve core to get the air out of the tire and use that same one again if they are unable to get the kit. GOOD LUCK!