The Diagnostic Executive contains software designed to allow the PCM to organize and prioritize the Main Monitor tests and procedures, and to record and display test results and diagnostic trouble codes.The functions controlled by this software include:
To control the diagnostic system so that the vehicle will continue to operate in a normal manner during testing.
To ensure that all of the OBD II Monitors run during the first two sample periods of the Federal Test Procedure.
To ensure that all OBD II Monitors and their related tests are sequenced so that required inputs (enable criteria) for a particular Monitor are present prior to running that particular Monitor.
To sequence the running of the Monitors to eliminate the possibility of different Monitor tests interfering with each other or upsetting normal vehicle operation.
To provide a Scan Tool interface by coordinating the operation of special tests or data requests.