  The one-loop contribution of the excited Kaluza-Klein (KK) modes of the
$SU_L(2)$ gauge group on the off-shell $WW\gamma$ and $WWZ$ vertices is
calculated in the context of a pure Yang-Mills theory in five dimensions and
its phenomenological implications discussed. The use of a gauge-fixing
procedure for the excited KK modes that is covariant under the standard gauge
transformations of the $SU_L(2)$ group is stressed. A gauge-fixing term and the
Faddeev-Popov ghost sector for the KK gauge modes that are separately invariant
under the standard gauge transformations of $SU_L(2)$ are presented. It is
shown that the one-loop contributions of the KK modes to the off-shell
$WW\gamma$ and $WWZ$ vertices are free of ultraviolet divergences and
well-behaved at high energies. It is found that for a size of the fifth
dimension of $R^{-1}\sim 1TeV$, the one-loop contribution of the KK modes to
these vertices is about one order of magnitude lower than the corresponding
standard model radiative correction. This contribution is similar to the one
estimated for new gauge bosons contributions in other contexts. Tree-level
effects on these vertices induced by operators of higher canonical dimension
are also investigated. It is found that these effects are lower than those
generated at the one-loop order by the KK gauge modes.
