The electrical diagram addresses power to the seat controls/track as well as the underseat computer.....you can get more electrical info on this at a Sebring retrofit into a Corvair (recommend you ignore the seat brackets devised to adapt the Sebring track to the Corvair track bolt points....no floor strength for the added loading)
http://www.corvairkid.com/sebring.htm
Note that the underseat computer feeds off the interior fuse box & must function when the door is opened....which unlocks the seat belts prior to sitting in the seat. Sebring is setup for either door to unlock the seat however the electrical diagram used in my 65 Dart is to only the left door....all at a nice price (I've bought 2 nice leather seats & computer & harness for $75 at a local junkyard)
Note that you must have a 98 or earlier seat computer......which is seperate from the main Sebring computer. Around 99 the seat function was moved to the Sebring main computer....you can use a 99 seat with a 98 or earlier seat computer for the retrofit.
The computer "decides" to lock up the belts if:
1) car is on a steep hill
2) car deceleration exceeds threshold
3) by timer after about 30 minutes
Orientation of the underseat computer is critical to properly sense the deceleration.
Getting the seat belts locked up earlier in a rapid deceleration than a normal setup seems like a nice safety feature.