This paper presents a study about q-ary product turbo codes applied to FFH-CDMA systems. A method to implement the q-ary soft decoding is proposed. First, an adaptation of Chase decoding algorithm to satisfy q-ary symbols requirements is developed. The adaptation does not significantly increase decoding complexity when compared to the binary algorithm. Second, a modification of iterative (turbo) decoding allows appropriate feedback of decoded q-ary symbols and their reliabilities in each decoder iteration. Simulation results indicate a good performance/complexity trade-off of the q-ary turbo coded system when compared to other previous proposed systems.