An Automated Digging Control System (ADCS) for a wheel loader is developed that utilizes a behavior-based control structure combined with fuzzy logic. This controller exhibits the real-time reactive responses necessary for executing digging tasks in an uncertain, unstructured and dynamic excavation environment. This paper presents field test results of a prototype ADCS that was developed and implemented on a Caterpillar 980G wheel loader. Test results show that the performance of the automated system is comparable to that of an expert human operator in a wide range of excavation situations.