Predissociation resonances of the radicals HCO and DCO were calculated using a three-dimensional (J=0) complex scaled discrete variable representation (DVR) method that was applied previously to a study of the weakly bound van der Waals complex NeICl [Lipkin, Moiseyev, and Leforestier, J. Chem. Phys. 98, 1888 (1993)]. This study represents a first application of the complex scaling method to a full dimensional chemical reactive system described by a fitted ab initio potential energy surface [Bowman, Bittman, and Harding, J. Chem. Phys. 85, 911 (1986)]. It is shown that the calculation method, being applied to a strongly coupled three-dimensional system, provides a unique criteria that makes it possible to identify all resonances in a given energy range as stationary solutions with respect to a complex variational parameter, independently of the resonance widths and their mutual overlapping. About 50 resonances were found for the radical HCO in the energy range between the ground and the second vibrational state of the product diatomic CO, whereas only half of them were located in recent calculations [Dixon, J. Chem. Sec. Faraday Trans. 88, 2575 (1992); Wang and Bowman, J. Chem. Phys. 100, 1021 (1994)]. It was found that the labeling procedure based on a spectroscopic Hamiltonian fit of the bound states and resonance positions agrees completely with the assignment of HCO resonances given in previous calculations, and provides an assignment for the whole set of calculated resonances. Eighty-three resonances of the radical DCO were found in the same energy range.