  Starting from the hypothesis that the $T_{cc}^+$ discovered at LHCb is a
$D^{\ast+} D^0/D^{\ast 0}D^+$ hadronic molecule, we consider the partial width
of its heavy quark spin partner, the $T_{cc}^{\ast +}$ as a $D^{\ast +} D^{\ast
0}$ shallow bound state, decaying into the $D^{\ast}D\pi$ final states
including the contributions of the $D^{\ast} D$ and $D^{\ast} \pi$ final state
interaction by using a nonrelativistic effective field theory. Because of the
existence of the $T_{cc}^+$ pole, the $I=0$ $D^{\ast} D$ rescattering can give
a sizeable correction up to about $40\%$ to the decay widths considering only
the tree diagrams, and the $D^{\ast} \pi$ rescattering correction is about
$10\%$. The four-body partial widths of the $T_{cc}^{*+}$ into $D D\pi\pi$ are
also explicitly calculated, and we find that the interference effect between
different intermediate $D^*D\pi$ states is small. The total width of the
$T_{cc}^{*+}$ is predicted to be about 41 keV.
