  We study the equivalence problem for CR-manifolds belonging to general class
III_2, i.e. the 5-dimensional CR-manifolds of CR-dimension 1 and codimension 3
whose CR-bundle satisfies a certain degeneracy condition. For such a
CR-manifold M, we construct a canonical Cartan connection on a 6-dimensional
principal bundle P on M. This provides a complete set of biholomorphic
invariants for M.
