Diagnostic Protocol Challenges in a Global Environment 2002-21-0023

Link-based diagnostics play a crucial role in servicing a vehicle's electrical system. This type of diagnostics relies on a communication protocol between an off-board tester and the vehicle's various electronic modules, such as the Powertrain Control Module (PCM). Within Ford Motor Company there are a number of diagnostic protocols used, such as J1850, ISO-9141, and newer ones based on CAN. The challenge for a single global diagnostic service tool (also referred to an “off-board tester”, or simply “tester” in this paper), such as Ford's Worldwide Diagnostic System (WDS), is to support various diagnostic protocols from North America, Europe, Asia-Pacific, and South Africa and provide high-quality diagnostics. This paper will discuss the various protocols and variations supported by Ford diagnostic service tools, methods used for testing and validation, and the long-term solution to this problem.