Ad hoc networks are collections of mobile nodes with links that are made or broken in an arbitrary way. They have no fixed infrastructure and, usually, have constrained resources. The next generation of IT applications is expected to rely heavily on such networks. However, before they can be successfully deployed several major security threats must be addressed. These threats are due mainly to the ad hoc nature of such networks. As a result it may be much harder (or even impossible) to establish routing paths that can tolerate Byzantine faults. Recently a Byzantine faults tracing protocol has been proposed. This combines a reliability metric based on passed history with an adaptive probing technique. In this paper we first show that such an approach is fundamentally flawed and cannot be used to detect malicious faults. We then propose a new tracing algorithm that exploits a basic property of broadcast channels, ping channels, and authentication mechanisms, to locate Byzantine faults.