Secondary Latch System - GMC 2005 Sierra Denali Owner's Manual

When you reinstall the regular wheel and tire, you must
also reinstall the center cap. Place the cap on the wheel
and tap it into place until it seats flush with the wheel. The
cap only goes on one way. Be sure to line up the tab on
the center cap with the indentation on the wheel.
8. Tighten the nuts firmly
in a crisscross
sequence as shown by
turning the wheel
wrench clockwise.

Secondary Latch System

Your vehicle has an underbody-mounted tire hoist
assembly equipped with a secondary latch system. It is
designed to stop the spare tire from suddenly falling
off your vehicle. For the secondary latch to work,
the spare must be installed with the valve stem pointing
down. See Storing a Flat or Spare Tire and Tools on
page 5-87.
5-83