In this paper we have proposed heuristic to address the problem of reducing congestion in presence of link fault in de Bruijn WDM networks. The proposed heuristic FTCRR (Fault Tolerant Congestion Reduced Routing), however can be directly extended for application to any other topology. Reducing congestion eventually results in conservation of channels in links. So the proposed heuristic will be extremely helpful in survivable logical topology design that demands setting up of additional lightpaths so that the network stays connected in presence of a link failure. To show the effectiveness of the proposed heuristic its performance is compared with FTGSR (Fault Tolerant Graph Search Routing) and GR (Greedy Routing). Performance comparisons show that FTCRR outperforms the other two heuristics.