Where is the main TPMS unit?
 

I was just curious, where is the central TPMS control unit located?

Also, if there is a TPMS failure, how would a service department know about it and verify? Does it throw a code? I doubt dealers will take it for a 15 mile highway trip to check for a malfunction.

check the tpms disable thread in the DIY forum, there's a drawing in there somewhere showing the location inside the dash.

code is strored-