  Second order scalar ordinary differential equations ({\sc ode}s) which are
linearizable possess special types of symmetries. These are the only symmetries
which are non fiber-preserving in the linearized form of the equation, and they
are called non-Cartan symmetries and known only for scalar {\sc ode}s. We give
explicit expressions of non-Cartan symmetries for systems of {\sc ode}s of
arbitrary dimensions and show that they form an abelian Lie algebra. It is
however shown that the natural extension of these non-Cartan symmetries to
arbitrary dimensions is applicable only to the natural extension of scalar
second order equations to higher dimensions, that is, to equivalence classes
under point transformations of the trivial vector equation. More precisely, it
is shown that non-Cartan symmetries characterize linear systems of {\sc ode}s
reducible by point transformation to their trivial counterpart, and we verify
that they do not characterize nonlinear systems of {\sc ode}s having this
property. It is also shown amongst others that the non-Cartan property of a
symmetry vector is coordinate-free. Some examples of application of these
results are discussed. %
