A diagnostic interface architecture for a memory device supports in one aspect one or more dynamically reconfigurable functional interconnects normally utilized in connection with reading data from the memory device and/or writing data to the memory device. The dynamically reconfigurable functional interconnects are capable of being configured to operate in either functional or diagnostic modes, whereby in the diagnostic mode, such interconnects may be used to communicate diagnostic information to support one or more diagnostic operations. The diagnostic interface architecture may also support multiple diagnostic interfaces in a given memory device, with at least one such diagnostic interface being capable of being selectively enabled in response to a failure in another diagnostic interface.