On Board Diagnostic Tests: Overview

A diagnostic test is a series of steps which has a beginning and end. The result of which is a pass or fail reported to the Diagnostic Executive. When a diagnostic test reports a pass result, the Diagnostic Executive records the following data:

^ The diagnostic test has completed since the last ignition cycle.
^ The diagnostic test has passed during the current ignition cycle.
^ The fault identified by the diagnostic test is not currently active.

When a diagnostic test reports a fail result, the Diagnostic Executive records the following data:

^ The diagnostic test has completed since the last ignition.
^ The fault identified by the diagnostic test is currently active.
^ The fault has been active during this ignition cycle.
^ The operating conditions at the time of the failure.