What Do We Know About OBDII Now?

Illinois has been testing OBDII systems with pass fail criteria for about a year now, and we know much more about how the system works or does not work than we knew in January 2004. But first a quick review... A vehicle that is presented for an OBDII test will first receive a gas cap test and then be scanned through the DLC. The vast majority of the vehicles will in fact communicate via the DLC and most that will not are either missing B+ on pin 16 and/or ground on pin 5. If the vehicle will communicate via the DLC, a check of applicable readiness monitors will occur. If the correct number of monitors have been run, MIL function is analyzed and the vehicle passes or fails. This abbreviated explanation gives an overview of the test. More information is available in the Outreach OBDII seminars.