[fibber2]

Being an indirect system, it's the wheel speed sensors (adjusted for by other inputs like the steering angle sensor) that are being compared to determine if a tire is low. When sitting still, there is no tire pressure input (no actual pressure sensors), no wheel speed sensor activity, etc. If you cannot get the system to null out even under these conditions, something else is wrong. May just be time to take it in.

 

[fibber2]

Interesting story! Too bad I don't believe a word of it. A Toyota dealer disabling a safety device rather than look for the root cause? Never!

Seriously, it sounds crazy enough to be true. I did some searching thru the only two electrical diagram sets that I have access to: 2004 (which doesn't seem to include the memory seat function) and the 2008 (by which time the TPMS system went to a transmitter system and has all new hardware and a separate computation unit. So while I got some ideas about power feeds, no smoking gun. It doesn't look like something obvious that they disconnected. However, Techstream (the computer interface) can query and switch quite a number of systems thru the body ECU. Perhaps there is a connection that they toggled.

Frankly, I'd make an appt with the service manager, sit down in the office, and go over all the details with him. They own you an answer. But given the liability they created, you still might not get them to fess up. You might end up having to open a case with National, as I sure your wife no longer trusts the van. Hell, if they really did this to you, you might end up as the new owner of the dealership!