Here you go...
Auto Lock
To display and select the AUTO LOCK Options
Press the OPTIONS button until AUTO LOCK appears on the display,
Press the RESET button to page through the following choices:
AUTO LOCK ON
In a manual transmission, both doors will automatically lock when the vehicle exceeds 10 mph (16 kph)
In a vehicle with an automatic transmission, both doors will automatically lock when you move the shifter out of PARK (P).
AUTO LOCK OFF
Choose AUTO LOCK OFF to turn this option off.
Found here...
http://www.safepic.com/corvette/dash2.htm#Auto%20Lock
Which has a root of...
http://www.safepic.com/corvette/
Speed