Results of an ab initio treatment of the Renner-Teller effect in the ground electronic state of HCCD+ are presented. The model Hamiltonian employed involves four nuclear degrees of freedom correlating at linear geometry with two degenerate bending vibrations. Computations of vibronic energy levels and wave functions are carried out by means of a variational approach. The results of calculations are compared with those for symmetric isotopic species HCCH+ and DCCD+.