I put a DCM3000 modem in a Magnum 290 today for Vehicle Sync.  The main power harness for the FMX is up in the roof and I didn't want to tear it all apart so I looked elsewhere for power.  Behind the seat to the left of the relays (when facing forward) is a power distribution center.  According to my meter the rear post is battery, the small stud to on the right is ground and the small stud on the left is switched power.  The modem turns on and appears to work but when I turn off the tractor key the modem stays on for a while.  Is this normal?  Do I have it hooked up incorrectly?