Standardisation of serial diagnostics

Standardisation of serial diagnostics may be considered at several levels from basic physical interconnection through signalling protocols to message content and, ultimately, diagnostic strategy. In Europe, standardisation attempts to date have been concentrated on the lower levels using ISO9141, although many nominally ISO9141 compliant installations still fall outside the bounds of that standard in some important respects. More recently, an ISO task force has been established to consider standardisation of diagnostic service message content, under the title Keyword Protocol 2000. Those who need to service vehicles from several manufacturers look to increasing standardisation at all levels as a way of reducing their reliance on special diagnostic tools, which they may be denied access to by tool cost or manufacturer distribution policy. Conversely, vehicle manufacturers may regard proprietary diagnostics as a method of granting their franchisees an advantage over independent sector competition, as a means of exercising control over sensitive areas such as late configuration of electronic controllers and as an easy option when designing or specifying systems. Legislation in the USA has attempted to enforce standardisation for emission-related diagnostics, whilst still respecting the legitimate concerns of vehicle manufacturers, by means of a layered approach: standard tools and data available to anybody allow vehicles to be diagnosed but the manufacturers are permitted to maintain proprietary control over so-called fast-track data and tools that facilitate the diagnostic process