Ok, to get the stupid stuff out of the way first. I never waited for the computer to tell me when to change the oil before. I understood the wrench icon for that, but the number threw me. Now that I'm home I've read the owners manual and understand it's "days to service" That eliminates that issue. Having both the wrench and the low tire pressure issue at the same time threw me.
On to the Tire pressure monitoring problem. I have the Service manual. After reading that, I understand why the DRBIII. It will tell the service person WHICH sensor is bad, when it ISN'T a tire pressure problem, or if it's the receiver in the car. It could also be a LOW BATTERY in the sensor. Only the DRBIII can diagnose problems with the system. It could be a BAD SENSOR, and the DRB will tell WHICH tire. It could be the receiver in the car. And for real grins, it could be that the battery needs replacing in the sensor inside the tire. In this case, the tire bead has to be broken and the sensor replaced. Whether it's bad, of just the battery doesn't matter. The battery is not replaceable according to the service manual. So, when I have time it's off to the dealer.